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/**********************************************************************
Audacity: A Digital Audio Editor
AVCodecContextWrapper.cpp
Dmitry Vedenko
**********************************************************************/
#include "AVCodecContextWrapper.h"
#include <cstring>
#include "FFmpegFunctions.h"
#include "AVCodecWrapper.h"
AVCodecContextWrapper::AVCodecContextWrapper(
const FFmpegFunctions& ffmpeg, std::unique_ptr<AVCodecWrapper> codec) noexcept
: mFFmpeg(ffmpeg)
, mAVCodec(std::move(codec))
, mIsOwned(true)
{
mAVCodecContext =
mFFmpeg.avcodec_alloc_context3(mAVCodec->GetWrappedValue());
}
AVCodecContextWrapper::AVCodecContextWrapper(
const FFmpegFunctions& ffmpeg, AVCodecContext* wrapped) noexcept
: mFFmpeg(ffmpeg)
, mAVCodecContext(wrapped)
, mIsOwned(false)
{
}
AVCodecContext* AVCodecContextWrapper::GetWrappedValue() noexcept
{
return mAVCodecContext;
}
const AVCodecContext* AVCodecContextWrapper::GetWrappedValue() const noexcept
{
return mAVCodecContext;
}
AVCodecContextWrapper::~AVCodecContextWrapper()
{
if (mIsOwned && mAVCodecContext != nullptr)
{
// avcodec_free_context, complementary to avcodec_alloc_context3, is
// not necessarily loaded
if (mFFmpeg.avcodec_free_context != nullptr)
{
mFFmpeg.avcodec_free_context(&mAVCodecContext);
}
else
{
// Its not clear how to avoid the leak here, but let's close
// the codec at least
if (mFFmpeg.avcodec_is_open(mAVCodecContext))
mFFmpeg.avcodec_close(mAVCodecContext);
}
}
}
std::vector<uint8_t>
AVCodecContextWrapper::DecodeAudioPacket(const AVPacketWrapper* packet)
{
auto frame = mFFmpeg.CreateAVFrameWrapper();
std::vector<uint8_t> data;
if (mFFmpeg.avcodec_send_packet == nullptr)
{
std::unique_ptr<AVPacketWrapper> packetCopy =
packet ? packet->Clone() : mFFmpeg.CreateAVPacketWrapper();
/*
"Flushing is done by calling this function [avcodec_decode_audio4]
with packets with avpkt->data set to NULL and avpkt->size set to 0
until it stops returning samples."
(That implies, not necessarily just one loop pass to flush)
*/
bool flushing = packet
? (packetCopy->GetSize() == 0 && packetCopy->GetData() == nullptr)
: true;
if (!flushing && packetCopy->GetData() == nullptr)
return {};
int bytesDecoded = 0;
do
{
int gotFrame;
// Deprecated? https://ffmpeg.org/doxygen/3.3/group__lavc__decoding.html#gaaa1fbe477c04455cdc7a994090100db4
bytesDecoded = mFFmpeg.avcodec_decode_audio4(
mAVCodecContext, frame->GetWrappedValue(), &gotFrame,
packetCopy->GetWrappedValue());
if (bytesDecoded < 0)
return data; // Packet decoding has failed
if (gotFrame == 0)
{
/*
"Note that this field being set to zero does not mean that an
error has occurred. For decoders with AV_CODEC_CAP_DELAY set, no
given decode call is guaranteed to produce a frame."
*/
// (Let's assume this doesn't happen when flushing)
// Still, the data was consumed by the decoder, so we need to
// offset the packet
packetCopy->OffsetPacket(bytesDecoded);
continue;
}
ConsumeFrame(data, *frame);
packetCopy->OffsetPacket(bytesDecoded);
}
while ( flushing ? bytesDecoded > 0 : packetCopy->GetSize() > 0 );
}
else
{
auto ret = mFFmpeg.avcodec_send_packet(
mAVCodecContext,
packet != nullptr ? packet->GetWrappedValue() : nullptr);
if (ret < 0)
// send_packet has failed
return data;
while (ret >= 0)
{
ret = mFFmpeg.avcodec_receive_frame(mAVCodecContext, frame->GetWrappedValue());
if (ret == AUDACITY_AVERROR(EAGAIN) || ret == AUDACITY_AVERROR_EOF)
// The packet is fully consumed OR more data is needed
break;
else if (ret < 0)
// Decoding has failed
return data;
ConsumeFrame(data, *frame);
}
}
return data;
}
void AVCodecContextWrapper::ConsumeFrame(
std::vector<uint8_t>& data, AVFrameWrapper& frame)
{
const int channels = GetChannels();
const auto sampleSize = static_cast<size_t>(mFFmpeg.av_get_bytes_per_sample(
static_cast<AVSampleFormatFwd>(frame.GetFormat())));
const auto samplesCount = frame.GetSamplesCount();
const auto frameSize = channels * sampleSize * samplesCount;
auto oldSize = data.size();
data.resize(oldSize + frameSize);
auto pData = &data[oldSize];
if (frame.GetData(1) != nullptr)
{
// We return interleaved buffer
for (int channel = 0; channel < channels; channel++)
{
for (int sample = 0; sample < samplesCount; sample++)
{
const uint8_t* channelData =
frame.GetExtendedData(channel) + sampleSize * sample;
uint8_t* output =
pData + sampleSize * (channels * sample + channel);
std::copy(channelData, channelData + sampleSize, output);
}
}
}
else
{
uint8_t* frameData = frame.GetData(0);
std::copy(frameData, frameData + frameSize, pData);
}
}
namespace
{
unsigned int MakeTag(char a, char b, char c, char d) noexcept
{
return
(static_cast<unsigned>(a) << 0) | (static_cast<unsigned>(b) << 8) |
(static_cast<unsigned>(c) << 16) | (static_cast<unsigned>(d) << 24);
}
}
void AVCodecContextWrapper::SetCodecTagFourCC(const char* fourCC) noexcept
{
if (fourCC == nullptr || std::strlen(fourCC) != 4)
return;
SetCodecTag(MakeTag(fourCC[0], fourCC[1], fourCC[2], fourCC[3]));
}
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