[FFmpeg-devel] [PATCH] libavformat/fifo: avoid repeated failure and recovery

[Marton Balint]

On Mon, 22 Nov 2021, Ryoji Gyoda wrote:

> If fifo_thread_recover() succeeds immediately after
> fifo_thread_dispatch_message() fails, the dts of the packet is scaled
> twice, causing cur_dts to be abnormally large and "Application provided
> invalid, non monotonically increasing dts to muxer in stream" to occur
> repeatedly.
>
> Steps to reproduce:
> 1. ffmpeg -f lavfi -i testsrc -c:v libx264 -map 0:v -flags +global_header -f fifo -fifo_format flv -attempt_recovery 1 -recover_any_error 1 rtmp://example.com/livekey
> 2. set a breakpoint on fifo_thread_recover
> 3. force disconnect from the rtmp server
> 4. wait for break
> 5. reconnect to the rtmp server
> 6. resume execution of ffmpeg
>
> Signed-off-by: Ryoji Gyoda <gy.cft4 at gmail.com>
> ---
> libavformat/fifo.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/fifo.c b/libavformat/fifo.c
> index 51d7fa5b94..e8caa6ec65 100644
> --- a/libavformat/fifo.c
> +++ b/libavformat/fifo.c
> @@ -183,6 +183,7 @@ static int fifo_thread_write_packet(FifoThreadContext *ctx, AVPacket *pkt)
>     AVFormatContext *avf2 = fifo->avf;
>     AVRational src_tb, dst_tb;
>     int ret, s_idx;
> +    int64_t orig_pts, orig_dts, orig_duration;
>
>     if (fifo->timeshift && pkt->dts != AV_NOPTS_VALUE)
>         atomic_fetch_sub_explicit(&fifo->queue_duration, next_duration(avf, pkt, &ctx->last_received_dts), memory_order_relaxed);
> @@ -198,14 +199,24 @@ static int fifo_thread_write_packet(FifoThreadContext *ctx, AVPacket *pkt)
>         }
>     }
>
> +    orig_pts = pkt->pts;
> +    orig_dts = pkt->dts;
> +    orig_duration = pkt->duration;
>     s_idx = pkt->stream_index;
>     src_tb = avf->streams[s_idx]->time_base;
>     dst_tb = avf2->streams[s_idx]->time_base;
>     av_packet_rescale_ts(pkt, src_tb, dst_tb);
>
>     ret = av_write_frame(avf2, pkt);
> -    if (ret >= 0)
> +    if (ret >= 0) {
>         av_packet_unref(pkt);
> +    }
> +    else {
> +        // avoid scaling twice
> +        pkt->pts = orig_pts;
> +        pkt->dts = orig_dts;
> +        pkt->duration = orig_duration;
> +    }
>     return ret;
> }
>

Thanks, applied.

Regards,
Marton