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<h1>Libquicktime API usage<br>
</h1>
</center>
<center><br>
<div style="text-align: left;"><a href="#1._API_Conventions">1. API
conventions</a><br>
<a href="#2._OpeningClosing">2. Opening/Closing</a><br>
<a href="#3._Reading_quicktime_files">3. Reading</a><br>
&nbsp;&nbsp;&nbsp; <a href="#3.1_Getting_audio_stream_information">3.1
Getting audio information</a><br>
&nbsp;&nbsp;&nbsp; <a href="#3.2_Decoding_audio">3.2 Decoding audio</a><br>
&nbsp;&nbsp;&nbsp; <a href="#3.3_Audio_seeking">3.3 Audio seeking</a><br>
&nbsp;&nbsp;&nbsp; <a href="#3.4_Getting_video_information">3.4
Getting video information</a><span style="font-weight: bold;"><br>
&nbsp;&nbsp;&nbsp; </span><a href="#3.5_Decoding_video">3.5 Decoding
video</a><br>
&nbsp;&nbsp;&nbsp; <a href="#3.6_Video_seeking">3.6 Video seeking</a><br>
&nbsp;&nbsp;&nbsp; <a href="#3.7_Global_information">3.7 Global
information</a><br>
<a href="#4._Writing_Quicktime_files">4. Writing</a><br>
&nbsp;&nbsp;&nbsp; <a href="#4.1_Setting_metadata">4.1 Setting metadata</a><br>
&nbsp;&nbsp;&nbsp; <a href="#4.2_Setting_up_tracks">4.2 Setting up
tracks</a><br>
&nbsp;&nbsp;&nbsp; <a href="#4.3_Setting_codec_parameters">4.3 Setting
codec parameters</a><br>
&nbsp;&nbsp;&nbsp; <a href="#4.4_Making_an_AVI">4.4 Making an AVI</a><br>
&nbsp;&nbsp;&nbsp; <a href="#4.5_Encoding_audio">4.5 Encoding audio</a><br>
&nbsp;&nbsp;&nbsp; <a href="#4.6_Encoding_video">4.6 Encoding video</a><br>
&nbsp;&nbsp;&nbsp; <a href="#4.7_Making_streamable_Quicktime">4.7
Making streamable quicktime</a><br>
<a href="#5._Colormodels">5. Colormodels</a><br>
<a href="#6._Codec_registry_interface">6. Codec registry interface</a><br>
</div>
</center>
<h3><a name="1._API_Conventions"></a>&nbsp;1. API Conventions<br>
</h3>
The libquicktime API is kept quite similar to the quicktime4linux API.
All libquicktime specific extensions are prefixed with lqt_ or LQT_.
Libquicktime makes however, a bit more use of enums. In this file, some
not recommended functions are not documented. Brave people might
consult the files <span style="font-family: monospace;">&lt;quicktime/quicktime.h&gt;</span>
and <span style="font-family: monospace;">&lt;quicktime/lqt.h&gt;</span>
for the whole truth.<br>
<h3><a name="2._OpeningClosing"></a>2. Opening/Closing</h3>
To open a Quicktime or sufficiently compatible AVI file, use:<br>
<br>
<code></code><span style="font-family: monospace;">quicktime_t*
quicktime_open(const char *filename, int rd, int wr);</span><br>
<br>
This returns an opaque pointer type quicktime_t* or NULL if the file
could not be opened. The returned handle is the first argument for most
libquicktime functions. The arguments <span
 style="font-family: monospace;">rd</span> and <span
 style="font-family: monospace;">wr</span> specify if the file
will be opened for reading or writing. Only one of both can be TRUE.
After you are done with it, close the handle with<br>
<br>
<span style="font-family: monospace;">int quicktime_close(quicktime_t
*file);</span><br>
<h3><a name="3._Reading_quicktime_files"></a>3. Reading quicktime files</h3>
<h4><a name="3.1_Getting_audio_stream_information"></a>3.1 Getting
audio information</h4>
First, get the number of audio streams with:<br>
<br>
<span style="font-family: monospace;">int
quicktime_audio_tracks(quicktime_t *file);</span><br>
<br>
Then, for each track, call:<br>
<br>
<span style="font-family: monospace;">int
quicktime_track_channels(quicktime_t *file, int track);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">long
quicktime_sample_rate(quicktime_t *file, int track);<br>
long quicktime_audio_length(quicktime_t *file, int track);<br
 style="font-family: monospace;">
</span><span style="font-family: monospace;">int
quicktime_audio_bits(quicktime_t *file, int track);</span><br>
<br>
to get channel count, the samplerate, length (in samples) and bits per
sample. The last
value is for information purposes only. While the audio format is
always available from the quicktime container, it can happen, that the
codec isn't supported by libquicktime. To make sure, that an audio
track can be decoded, check if the return value of<br>
<br>
<span style="font-family: monospace;">int
quicktime_supported_audio(quicktime_t *file, int track)</span>;<br>
<br>
is nonzero. Then, before you decode the first samples, you can set some
codec parameters. This works exactly the same way as for encoding (see <a
 href="#4.3_Setting_codec_parameters">Setting codec parameters</a>).<br>
<h4><a name="3.2_Decoding_audio"></a>3.2 Decoding audio</h4>
There are 3 functions for decoding audio. The most recommended one is:<br>
<br>
<span style="font-family: monospace;">int
lqt_decode_audio_track(quicktime_t *file, int16_t **output_i, float
**output_f, long samples, int track);</span><br>
<br>
<span style="font-family: monospace;">output_i</span> and <span
 style="font-family: monospace;">output_f</span> are pointers to arrays
where the samples for the channels will be copied. Either of both
arrays can be NULL.
Single channel arrays can also be NULL if some channels are not of
interest.<br>
The quicktime4linux API (unlike ours) hides the concept of an audio
track from the user. To resemble this behaviour, there is a function:<br>
<br>
<span style="font-family: monospace;">int lqt_decode_audio(quicktime_t
*file, int16_t **output_i, float **output_f, long samples);</span><br>
<br>
It decodes all channels of all tracks at once. Finally, there is the
quicktime4linux approach (for compatibility reasons):<br>
<br>
<span style="font-family: monospace;">int
quicktime_decode_audio(quicktime_t *file, int16_t *output_i, float
*output_f, long samples, int channel);</span><br>
<br>
It's not recommended, because if you need more than one channel, you
must seek backwards between the decode calls.<br>
After decoding, you can use<br>
<br>
<span style="font-family: monospace;">int64_t
lqt_last_audio_position(quicktime_t * file, int track);</span><br>
<br>
It returns the REAL sample position of the stream. You can use this to
check, if you decoded fewer samples than you wanted. In this case, EOF
is reached.<br>
<h4><a name="3.3_Audio_seeking"></a>3.3 Audio seeking</h4>
To set an audio stream to a specified position, use:<br>
<br>
<span style="font-family: monospace;">int
quicktime_set_audio_position(quicktime_t *file, int64_t sample, int
track);</span><br>
<br>
Subsequent decode calls will then start from the specified sample
position. Seeking is sample-accurate except for AVI files with
compressed audio due to file format weaknesses.<br>
<h4><a name="3.4_Getting_video_information"></a>3.4 Getting video
information</h4>
First, get the number of video tracks with:<br>
<br>
<span style="font-family: monospace;">int
quicktime_video_tracks(quicktime_t *file);<span
 style="font-weight: bold;"><br>
<br>
</span></span>For each track, get the video format with:<span
 style="font-weight: bold;"><br>
<br>
</span><span style="font-family: monospace;">int
quicktime_video_width(quicktime_t *file, int track);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">int
quicktime_video_height(quicktime_t *file, int track);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">int
lqt_video_time_scale(quicktime_t * file, int track);</span><span
 style="font-weight: bold;"><br>
</span><span style="font-family: monospace;">double
quicktime_frame_rate(quicktime_t *file, int track);<br>
long quicktime_video_length(quicktime_t *file, int track);<br>
int64_t lqt_video_duration(quicktime_t * file, int track);<br>
int quicktime_video_depth(quicktime_t *file, int track);<br>
<br>
</span>The last function is for information only. You can either use
the framerate (and <span style="font-family: monospace;">quicktime_video_length</span>)
for your synchronization or the timescale (and <span
 style="font-family: monospace;">lqt_video_duration</span>). The
timescale method has the advantage, that you make no rounding
errors and can synchronize tracks with nonconstant framerates. While
the video format is always available from the quicktime
container, it can happen, that the codec isn't supported by
libquicktime. To make sure, that a video track can be decoded, check
if the return value of<br>
<br>
<span style="font-family: monospace;">int
quicktime_supported_video(quicktime_t *file, int track)</span>;<br>
<br>
is nonzero. Then, before you decode the first frame, you can set some
codec
parameters. This works exactly the same way as for encoding (see <a
 href="file:///home/pix/Src/Libquicktime/libquicktime/doc/api_usage.html#4.3_Setting_codec_parameters">Setting
codec parameters</a>).
<h4><a name="3.5_Decoding_video"></a>3.5 Decoding video</h4>
After you figured out the proper colormodel (see <a
 href="#5._Colormodels">colormodels</a>) and before decoding the first
frame, call:<br>
<br>
<span style="font-family: monospace;">lqt_set_cmodel(<span
 style="font-family: monospace;">quicktime_t *file, int track, int
colormodel);</span><br>
</span><br>
Furthermore, you might have planar video frames (e.g. XVideo images)
which have padded scanlines. To tell this to the library, use:<br>
<br>
<span style="font-family: monospace;">void lqt_set_row_span(quicktime_t
*file, int track, int row_span);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">void
lqt_set_row_span_uv(quicktime_t *file, int track, int row_span_uv);</span><br>
<br>
The first one sets the byte offsets between the scane lines for the
luminance plane, the second one is for the chrominance planes. Then,
you
can get the timestamp and duration of the NEXT frame to be decoded with:<br>
<br>
<span style="font-family: monospace;">int64_t
lqt_frame_time(quicktime_t * file, int track);</span><br>
<br>
The unit are timescale tics. Finally, decode the frame with:<br>
<br>
<span style="font-family: monospace;">int lqt_decode_video(quicktime_t
*file, unsigned char **row_pointers, int track);</span><br>
<br>
<span style="font-family: monospace;">row_pointers</span> points to the
scanline beginnings for packed formats and
to the planes for planar formats. Alternatively, you can use:<br>
<br>
<span style="font-family: monospace;">long
quicktime_decode_scaled(quicktime_t *file,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int in_x,&nbsp; /* Location of input frame to take picture */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int in_y,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int in_w,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int in_h,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int out_w, /* Dimensions of output frame */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int out_h,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int color_model,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
unsigned char **row_pointers,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int track);</span><br>
<br>
It lets you take a rectangular area from the file and writes it into
the buffer at a specified location. If input size and output size are
different, the image will be scaled. Finally, there is a legacy
version, which will only work for BC_RGB888:<br>
<br>
<span style="font-family: monospace;">int
quicktime_decode_video(quicktime_t *file,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
unsigned char **row_pointers,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int track);</span><br>
<h4><a name="3.6_Video_seeking"></a>3.6 Video seeking</h4>
There are different approaches depending on your timing method.<br>
<br>
<span style="font-family: monospace;">lqt_seek_video(quicktime_t *
file, int track, </span><span style="font-family: monospace;">int64_t
time);</span><br style="font-family: monospace;">
<br>
seeks to the specified time given in timescale tics. Since the
timestamp of the next frame might be slightly different from<br>
the time you seeked to, use <span style="font-family: monospace;">lqt_frame_time
</span>to get the timestamp of the next frame. If you trust the
framerate and just count frames, you can use:<br>
<br>
<span style="font-family: monospace;">int
quicktime_set_video_position(quicktime_t *file, int64_t frame, int
track);</span><br>
<h4><a name="3.7_Global_information"></a>3.7 Global information</h4>
These are for information only. They play no role in the decoding
process. To find out, if the file is an AVI, use<br>
<br>
<span style="font-family: monospace;">int lqt_is_avi(quicktime_t *file);<br>
<br>
</span>Then, you can get the metadata as strings:<br>
<br>
<span style="font-family: monospace;">char*
quicktime_get_copyright(quicktime_t *file);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">char*
quicktime_get_name(quicktime_t *file);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">char*
quicktime_get_info(quicktime_t *file);</span><br>
<span style="font-family: monospace;">char * lqt_get_album(quicktime_t
* file);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">char * lqt_get_artist(quicktime_t
* file);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">char * lqt_get_genre(quicktime_t
* file);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">char * lqt_get_track(quicktime_t
* file);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">char *
lqt_get_comment(quicktime_t *file);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">char * lqt_get_author(quicktime_t
*file);</span><br>
<br>
Treat the return values as if they were const. No, libquicktime isn't
really const friendly ;-(<br>
<h3><a name="4._Writing_Quicktime_files"></a>4. Writing Quicktime files</h3>
<h4><a name="4.1_Setting_metadata"></a>4.1 Setting metadata</h4>
First, you might want to insert some information strings into your
file. Do this with:<br>
<br>
<span style="font-family: monospace;">void
quicktime_set_copyright(quicktime_t *file, char *string);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">void
quicktime_set_name(quicktime_t *file, char *string);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">void
quicktime_set_info(quicktime_t *file, char *string);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">void lqt_set_album(quicktime_t
*file, char *string);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">void lqt_set_artist(quicktime_t
*file, char *string);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">void lqt_set_genre(quicktime_t
*file, char *string);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">void lqt_set_track(quicktime_t
*file, char *string);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">void lqt_set_comment(quicktime_t
*file, char *string);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">void lqt_set_author(quicktime_t
*file, char *string);</span><span style="font-weight: bold;"><br>
</span>
<h4><a name="4.2_Setting_up_tracks"></a>4.2 Setting up tracks</h4>
To add an audio track, call:<br>
<br>
<span style="font-family: monospace;">int
lqt_add_audio_track(quicktime_t *file,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int channels, long
sample_rate, int bits, lqt_codec_info_t * info);</span><br>
<br>
The bits argument is only relevant for the twos and sowt codecs. It
should be set to 16 by default. To add a video track, use:<br>
<br>
<span style="font-family: monospace;">int
lqt_add_video_track(quicktime_t *file,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int frame_w, int frame_h,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int frame_duration, int timescale,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
lqt_codec_info_t * info);</span><br>
<br>
The <span style="font-family: monospace;">frame_duration</span> should
is only important, if you use
<span style="font-family: monospace;">quicktime_encode_video</span>
(see below).<br>
<br>
<h4><a name="4.3_Setting_codec_parameters"></a>4.3 Setting codec
parameters</h4>
To set a parameter of audio and video codecs, call<br>
<br>
<span style="font-family: monospace;">void
lqt_set_audio_parameter(quicktime_t *file,int stream, char *key,void
*value);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">void
lqt_set_video_parameter(quicktime_t *file,int stream, char *key,void
*value);</span><br>
<br>
value must be of type <span style="font-family: monospace;">char*</span>
for string parameters and <span style="font-family: monospace;">int*</span>
for integer parameters. See <a href="#6._Codec_registry_interface">Codec
registry interface</a> for methods to find out the encoding parameters.<br>
<h4><a name="4.4_Making_an_AVI"></a>4.4 Making an AVI</h4>
After you configured all codecs, you can tell the library to make an
AVI instead of a Quicktime file. It's done with:<br>
<br>
<span style="font-family: monospace;">void
quicktime_set_avi(quicktime_t *file, 1);</span><br
 style="font-family: monospace;">
<br>
Please note, that not all codecs are supported with AVI files. Some are
only supported in AVIs. See <a href="#6._Codec_registry_interface">Codec
registry interface</a> for more informtation about this.<br>
<h4><a name="4.5_Encoding_audio"></a>4.5 Encoding audio</h4>
To encode a buffer full of samples, use<br>
<br>
<span style="font-family: monospace;">int
lqt_encode_audio_track(quicktime_t *file,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int16_t **channels_i,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
float **channels_f,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
long samples,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int track);</span><br style="font-family: monospace;">
<br>
Either channels_i or channels_f must be NULL.<br>
<h4><a name="4.6_Encoding_video"></a>4.6 Encoding video</h4>
Before you encode the first frame, you must decide which colormodel you
use (see <a href="#5._Colormodels">Colormodels</a>). You tell the
library about the colormodel with:<br>
<br>
<span style="font-family: monospace;">void lqt_set_cmodel(quicktime_t
*file, int track, int colormodel);</span><br>
<br>
Then, if you will use a planar format, and your memory had padded
scanlines, tell the byte offsets between the scanlines of the luminance
and chrominance planes:<br>
<br>
<span style="font-family: monospace;">void lqt_set_row_span(quicktime_t
*file, int track, int row_span);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">void
lqt_set_row_span_uv(quicktime_t *file, int track, int row_span_uv);</span><br
 style="font-family: monospace;">
<br>
Finally, if you source has individual tinestamps for all frames, call<br>
<br>
<span style="font-family: monospace;">int lqt_encode_video(quicktime_t
*file,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
unsigned char **row_pointers,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int track, int64_t time);</span><br style="font-family: monospace;">
<br>
The timestamp is given in timescale tics. <span
 style="font-family: monospace;">row_pointers</span> contains the
scanlines for packet formats and the planes <br>
for planar formats. If you have a constant frame duration and passed it
to <span style="font-family: monospace;">lqt_add_video_track</span>,
you might also use:<br>
<br>
<span style="font-family: monospace;">int
quicktime_encode_video(quicktime_t *file,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
unsigned char **row_pointers,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int track);<br>
</span>
<h4><a name="4.7_Making_streamable_Quicktime"></a>4.7 Making streamable
Quicktime</h4>
By default, libquicktime will put the header (the moov atom) at the end
of the file. This means, that it won't be playable from a non-seekable
source (i.e. a http connection). To reorder the file to have the header
at the start, call:<br>
<br>
<span style="font-family: monospace;">int
quicktime_make_streamable(char *in_path, char *out_path);<br>
<br>
</span>This function must be called after you closed the file with <span
 style="font-family: monospace;">quicktime_close</span>. Note that you
need twice the disk space for this function.<span
 style="font-family: monospace;"><br>
</span>
<h3><a name="5._Colormodels"></a>5. Colormodels</h3>
The supported colormodels are defined in colormodels.h. Libquicktime
adds another value <span style="font-family: monospace;">LQT_COLORMODEL_NONE</span>,
which specifies an uninitialized or unknown colormodel. Informations
about the supported colormodels can be obtained with:<br>
<br>
<span style="font-family: monospace;">const char *
lqt_colormodel_to_string(int colormodel);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">int
lqt_string_to_colormodel(const char * str);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">int lqt_colormodel_is_planar(int
colormodel);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">int lqt_colormodel_has_alpha(int
colormodel);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">int lqt_colormodel_is_rgb(int
colormodel);</span><br style="font-family: monospace;">
<span style="font-family: monospace;">int lqt_colormodel_is_yuv(int
colormodel);</span><br style="font-family: monospace;">
<span style="font-family: monospace;"><br>
int lqt_num_colormodels();</span><br style="font-family: monospace;">
<span style="font-family: monospace;">const char *
lqt_get_colormodel_string(int index);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">int lqt_get_colormodel(int index);</span><br
 style="font-family: monospace;">
<br>
The best idea is to decide, which colormodels you want to support in
your application. <span style="font-family: monospace;">BC_RGB888</span>
and <span style="font-family: monospace;">BC_YUV420P</span> should
always be supported. Please note, that libquicktimes internal
colorspace converter is not the fastest out there. The more colorspaces
you can handle yourself, the fewer time consuming internal conversions
will be used. A nice library, which converts many
libquicktime colormodels, is <a
 href="http://gmerlin.soutceforge.net/gavl.html">gavl</a>. Then call
for each video track:<br>
<br>
<span style="font-family: monospace;">int
lqt_get_best_colormodel(quicktime_t * file, int track, int * supported);</span><br>
<br>
<span style="font-family: monospace;">supported</span> is an array of
the colorspaces, you can handle terminated with <span
 style="font-family: monospace;">LQT_COLORMODEL_NONE</span>. The
function works for both en- and decoding and tries to minimize
conversion overhead and information loss.<br>
<h3><a name="6._Codec_registry_interface"></a>6. Codec registry
interface</h3>
This allows you to access the codecs, which are installed on the system
along with information about them. To query the registry about the
installed codecs, use:<br>
<br>
<span style="font-family: monospace;">lqt_codec_info_t **
lqt_query_registry(int audio, int video,</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int encode, int decode);</span><br style="font-family: monospace;">
<br>
The return value is a NULL terminated array of <span
 style="font-family: monospace;">lqt_codec_info_t</span> pointers. The
codec info is defined in lqt_codecinfo.h:<br>
<br>
<span style="font-family: monospace;">typedef struct lqt_codec_info_s
lqt_codec_info_t;<br>
<br style="font-family: monospace;">
</span><span style="font-family: monospace;">struct lqt_codec_info_s</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; {</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; int compatibility_flags;
/* Compatibility flags (See defines above) */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; </span><span
 style="font-family: monospace;">char *
name;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
/* Name of the
codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
*/</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; char *
long_name;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /*
Long name of the codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
*/</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; char *
description;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /*
Description&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
*/</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;</span><span
 style="font-family: monospace;"> lqt_codec_type type;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; lqt_codec_direction
direction;</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int
num_fourccs;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
/* Fourccs, this codec can handle */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; char ** fourccs;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int num_wav_ids;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; int * wav_ids;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int num_encoding_parameters;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; lqt_parameter_info_t *
encoding_parameters;</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int num_decoding_parameters;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; lqt_parameter_info_t *
decoding_parameters;</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; /* Colormodels this codec can
handle */</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int num_encoding_colormodels;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; int * encoding_colormodels;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;"></span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int decoding_colormodel;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; /* The following members are
set by libquicktime&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; char *
module_filename;&nbsp;&nbsp;&nbsp; /* Filename of the module&nbsp; */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; int
module_index;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /*
Index inside the module */</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; uint32_t
file_time;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* File
modification time&nbsp; */</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; struct lqt_codec_info_s *
next;&nbsp;&nbsp; /* For chaining */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; };</span><br
 style="font-family: monospace;">
<br style="font-family: monospace;">
Most interesting are the name, long name and description. The <span
 style="font-family: monospace;">encoding_parameters</span> and <span
 style="font-family: monospace;">decoding_parameters</span> arrays
contain informations about the parameters you can pass to
lqt_set_[audio|video]_parameter. The parameter infos are defined like
this:<br>
<br>
<span style="font-family: monospace;">typedef enum</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; {</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;
LQT_PARAMETER_INT,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;
LQT_PARAMETER_STRING,</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;
LQT_PARAMETER_STRINGLIST, /* String with options */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp; /* This dummy
type is used to separate sections (real_name will be on tab-label) */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;
LQT_PARAMETER_SECTION</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; } lqt_parameter_type_t;</span><br
 style="font-family: monospace;">
<br style="font-family: monospace;">
<span style="font-family: monospace;">typedef union</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; {</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; int val_int;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; char * val_string;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; } lqt_parameter_value_t;</span><br
 style="font-family: monospace;">
<br style="font-family: monospace;">
<span style="font-family: monospace;">typedef struct</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; {</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; /* Parameter name (to be
passed to quicktime_set_parameter() ) */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; char * name;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; char * real_name; /* Other
name (for making dialogs) */</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; lqt_parameter_type_t type;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; lqt_parameter_value_t
val_default;</span><br style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; /*</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp; *&nbsp;&nbsp;
Minimum and maximum values:</span><br style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp; *&nbsp;&nbsp; These
are only valid for numeric types and if val_min &lt; val_max</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp; */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int val_min;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; int val_max;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; /*</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp; *&nbsp; Possible
options (only valid for LQT_STRINGLIST)</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp;&nbsp; */</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; int num_stringlist_options;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">&nbsp; char ** stringlist_options;</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;"></span><span
 style="font-family: monospace;">&nbsp; } lqt_parameter_info_t;</span><br
 style="font-family: monospace;">
<br>
You can also get the codec infos, when you read a file:<br>
<br>
<span style="font-family: monospace;">lqt_codec_info_t **
lqt_audio_codec_from_file(quicktime_t *, int track);</span><br
 style="font-family: monospace;">
<span style="font-family: monospace;">lqt_codec_info_t **
lqt_video_codec_from_file(quicktime_t *, int track);</span><br>
<br>
Codec infos are returned as a local copy, so you must free them. This
is done with:<br>
<br>
<span style="font-family: monospace;">void
lqt_destroy_codec_info(lqt_codec_info_t ** info);</span><br>
<br>
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