When I run my demo code I get these warnings when testing it on a webm video:

[opus @ 0x5ec0fc1b4580] Could not update timestamps for skipped samples.
[opus @ 0x5ec0fc1b4580] Could not update timestamps for discarded samples.

But it’s not limited to webm, I also get this warning when running with a mp4:

[aac @ 0x61326fb83700] Could not update timestamps for skipped samples.

I know I’m getting warnings because ffmpeg must be skipping packets, but I have no idea why. Why are we skipping packets (and if that’s not the problem, what is) and how can we fix the problem?

Here’s my code for context:

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>

int main()
{
    int ret = 0;

    const AVCodec* codec;
    AVFormatContext* fmt_ctx = avformat_alloc_context();

    const char* file2 = "/home/aabiji/Videos/sync-test.webm";
    if ((ret = avformat_open_input(&fmt_ctx, file2, NULL, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "Couldn't open input filen");
        return -1;
    }

    ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, &codec, 0);
    if (ret < 0) {
        av_log(NULL, AV_LOG_ERROR, "Couldn't find a media streamn");
        return -1;
    }

    int stream_index = ret;
    AVStream* media = fmt_ctx->streams[stream_index];

    AVCodecContext* codec_context = avcodec_alloc_context3(codec);
    if (avcodec_parameters_to_context(codec_context, media->codecpar) < 0) {
        return -1;
    }

    if ((ret = avcodec_open2(codec_context, codec, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "Couldn't open media decodern");
        return -1;
    }

    AVPacket* packet = av_packet_alloc();
    AVFrame* frame = av_frame_alloc();

    while ((ret = av_read_frame(fmt_ctx, packet)) >= 0) {
        if (packet->stream_index != stream_index) {
            continue;
        }

        ret = avcodec_send_packet(codec_context, packet);
        if (ret < 0) {
            break; // Error
        }

        while (ret >= 0) {
            ret = avcodec_receive_frame(codec_context, frame);
            if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN)) {
                break;
            } else if (ret < 0) {
                fprintf(stderr, "Error during decodingn");
                break;
            }
            av_frame_unref(frame);
        }

        av_packet_unref(packet);
    }

    avcodec_flush_buffers(codec_context);

    av_packet_unref(packet);
    av_frame_free(&frame);
    av_packet_free(&packet);
    avcodec_free_context(&codec_context);
    avformat_close_input(&fmt_ctx);
    return 0;
}