I made my own rtmp server using libav and ffmpeg. I receive as input either an flv file or an rtmp streaming "containing" an flv file. Since I manipulate the flv file and the relative composition time of each frame, I would like to know if there is a way to get this composition time. I thought that given my AVPacket, I could analyze the raw buffer in order to extract the right information since I know that the flv header is 11 bytes and then in the next 16 bytes I should find the composition time. But it doesn't work.
This is a rough example of code:
AVPacket pkt;
AVFormatContext *ifmt_ctx
while(true)
{
AVStream *in_stream, *out_stream;
ret = av_read_frame(ifmt_ctx, &pkt);
//get the composite time
}
AVPacket needs to be able to represent the data found in all media formats. Some formats (like mp4 and flv) have a decode_time and a composition_time, other (like transport streams) have a decode_time and a presentation_time. To make it easier for the programmer, AVPacket chose one method to store the information and converts when needed. Luckily its an an easy to convert back:
auto cts = pkt.pts - pkt.dts