How to FFmpeg decode and extract metadata from last frame?

Question

I am decoding using FFMpeg. The videos I am decoding are H.264 or MPEG4 videos using C code. I am using the 32bit libs. I have successfully decoded and extracted the metadata for the first frame. I would now like to decode the last frame. I have a defined duration of the video, and felt it was a safe assumption to say that isLastFrame = duration . Here's what I have, any suggestions?

AVFormatContext* pFormatCtx = avformat_alloc_context();
avformat_open_input(&pFormatCtx, filename, NULL, NULL);
int64_t duration = pFormatCtx->duration;
i=0;
while(av_read_frame(pFormatCtx, &packet)>=0) {
   /* Is this a packet from the video stream? */
   if(packet.stream_index==videoStream) {
   /* Decode video frame*/
      avcodec_decode_video2(pCodecCtx, pFrame, &duration, &packet);
    }

Any help is much appreciated! :)

Answer 1

Thanks everyone for your help but I found that the reason the AV_SEEK_FRAME duration wasn't working was because you must multiply it by 1000 for it to be applicable in read frame. Also please note that the reason I have but decode_video instead of the decode functions calls is because I was using 32 bit and created my own but if you plug in video_decode() or I believe it's decode_video2 it works just as well. Hopefully this will help any fellow decoders in the future.

AVFormat Format;
int64_t duration = Format->duration;
duration = duration * 1000;
if (av_seek_frame(Format, Packet->stream_index, duration, AVSEEK_FLAG_ANY) <= 0)
    {
        /* read the frame and decode the packet */
        if (av_read_frame(FormatContext, &Packet) >= 0)
        {
            /*decode the video frame*/
            decode_video(CodecContext, Frame, &duration, &Packet);

        }

Answer 2

This might be what you're looking for:

Codecs which have the CODEC_CAP_DELAY capability set have a delay between input and output, these need to be fed with avpkt->data=NULL, avpkt->size=0 at the end to return the remaining frames.

Link to FFmpeg documentation