[FFmpeg-devel] [PATCH] avformat/rtpdec_rfc4175: fix interlace format

[lance.lmwang at gmail.com]

On Wed, Feb 02, 2022 at 03:45:10PM -0500, Patrick Keroulas wrote:
> In previous state, a new frame was allocated on each timestamp step,
> i.e. each frame/field transition. However, for interlace, a new frame
> should be allocated on 1st field, completed with the 2nd and finally
> freed.
> 
> This commit fixes the frame allocation and the detection of missing RTP
> markers.
> 
> Signed-off-by: Patrick Keroulas <patrick.keroulas at radio-canada.ca>
> ---
>  libavformat/rtpdec_rfc4175.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/libavformat/rtpdec_rfc4175.c b/libavformat/rtpdec_rfc4175.c
> index 8e73c07838..83abe499f8 100644
> --- a/libavformat/rtpdec_rfc4175.c
> +++ b/libavformat/rtpdec_rfc4175.c
> @@ -234,20 +234,21 @@ static int rfc4175_handle_packet(AVFormatContext *ctx, PayloadContext *data,
>      uint8_t *dest;
>  
>      if (*timestamp != data->timestamp) {
> -        if (data->frame) {
> +        if (data->frame && (!data->interlaced || data->field)) {
>              /*
> -             * if we're here, it means that two RTP packets didn't have the
> -             * same timestamp, which is a sign that they were packets from two
> -             * different frames, but we didn't get the flag RTP_FLAG_MARKER on
> -             * the first one of these frames (last packet of a frame).
> -             * Finalize the previous frame anyway by filling the AVPacket.
> +             * if we're here, it means that we missed the cue to return
> +             * the previous AVPacket, that cue being the RTP_FLAG_MARKER
> +             * in the last packet of either the previous frame (progressive)
> +             * or the previous second field (interlace). Let's finalize the
> +             * previous frame (or pair of fields) anyway by filling the AVPacket.
>               */
>              av_log(ctx, AV_LOG_ERROR, "Missed previous RTP Marker\n");
>              missed_last_packet = 1;
>              rfc4175_finalize_packet(data, pkt, st->index);
>          }
>  
> -        data->frame = av_malloc(data->frame_size);
> +        if (!data->frame)
> +            data->frame = av_malloc(data->frame_size);
>  
>          data->timestamp = *timestamp;

LGTM 

>  
> -- 
> 2.25.1
> 

-- 
Thanks,
Limin Wang