libav modification of libavformat/utils.c providing support for unexpected stream termination in live RTSP or similar video streams.

gistfile1.txt

// Inside the file libavformat/utils.c is the routine "int av_read_frame(AVFormatContext *s, AVPacket *pkt)", one of the key routines
// used to play video streams through FFMPEG's libav. This routine does not handle the situation when a live stream terminates 
// unexpectedly, such as the unplugging of a network connection, power loss to a camera, or other reasons an established connection
// would unexpectedly stop delivering packets. 
// Below is the beginning of av_read_frame() up to and a bit past the three added lines necessary to support calling of the installed
// avformat interrupt callback. The conventional libav behavior is to call the avformat interrupt callback while establishing a new
// connection with a live stream. It is not called while the stream is playing, therefore no opportunity is provided to the client
// software to recognise unexpected stream termination.
// The three lines are added to the code pasted below. They should be easy to identify:

int av_read_frame(AVFormatContext *s, AVPacket *pkt)
{
    const int genpts = s->flags & AVFMT_FLAG_GENPTS;
    int eof = 0;
    int ret;
    AVStream *st;

    if (!genpts) {
        ret = s->internal->packet_buffer
              ? read_from_packet_buffer(&s->internal->packet_buffer,
                                        &s->internal->packet_buffer_end, pkt)
              : read_frame_internal(s, pkt);
        if (ret < 0)
            return ret;
        goto return_packet;
    }

    for (;;) {

//
// Blake Senftner modification for CyberExtruder see libav-user 2/1/2017
        if (ff_check_interrupt(&s->interrupt_callback)) {
                ret = AVERROR_EXIT;
                av_log(s, AV_LOG_DEBUG, "interrupted\n" );
                return ret;
        }
// end Blake modification
//

        AVPacketList *pktl = s->internal->packet_buffer;

        if (pktl) {
            AVPacket *next_pkt = &pktl->pkt;

            if (next_pkt->dts != AV_NOPTS_VALUE) {
                int wrap_bits = s->streams[next_pkt->stream_index]->pts_wrap_bits;
                // last dts seen for this stream. if any of packets following
                // current one had no dts, we will set this to AV_NOPTS_VALUE.
                int64_t last_dts = next_pkt->dts;
                av_assert2(wrap_bits <= 64);
                while (pktl && next_pkt->pts == AV_NOPTS_VALUE) {