ffmpeg(libavcodec). memory leaks in avcodec_encode_video - c++

Question

I'm trying to transcode a video with help of libavcodec.
On transcoding big video files(hour or more) i get huge memory leaks in avcodec_encode_video. I have tried to debug it, but with different video files different functions produce leaks, i have got a little bit confused about that :). Here FFMPEG with QT memory leak is the same issue that i have, but i have no idea how did that person solve it. QtFFmpegwrapper seems to do the same i do(or i missed something).
my method is lower. I took care about aFrame and aPacket outside with av_free and av_free_packet.
int
Videocut::encode(
AVStream *anOutputStream,
AVFrame *aFrame,
AVPacket *aPacket
)
{
AVCodecContext *outputCodec = anOutputStream->codec;
if (!anOutputStream ||
!aFrame ||
!aPacket)
{
return 1;
/* NOTREACHED */
}
uint8_t * buffer = (uint8_t *)malloc(
sizeof(uint8_t) * _DefaultEncodeBufferSize
);
if (NULL == buffer) {
return 2;
/* NOTREACHED */
}
int packetSize = avcodec_encode_video(
outputCodec,
buffer,
_DefaultEncodeBufferSize,
aFrame
);
if (packetSize < 0) {
free(buffer);
return 1;
/* NOTREACHED */
}
aPacket->data = buffer;
aPacket->size = packetSize;
return 0;
}

Answer 1

The first step would be to try to reproduce your problem under Valgrind on a Linux box, if you can.
ffmpeg encoders and decoders usually not dynamically allocate memory; they reuse buffers between calls. Leaks are usually going to be in the frames somewhere.
Note that av_free_packet will only free your dynamically allocated buffer if the packet has a destructor function!
Look at how the function is defined in libavcodec/avpacket.c:
void av_free_packet(AVPacket *pkt)
{
if (pkt) {
if (pkt->destruct) pkt->destruct(pkt);
pkt->data = NULL; pkt->size = 0;
pkt->side_data = NULL;
pkt->side_data_elems = 0;
}
}
If there is no pkt->destruct function, no clean up takes place!