[FFmpeg-devel] [PATCH 1/1] Sega FILM: set dts and duration when demuxing

Michael Niedermayer michael at niedermayer.cc
Thu Mar 22 00:53:55 EET 2018


On Wed, Mar 21, 2018 at 09:14:44AM -0700, misty at brew.sh wrote:
> From: Misty De Meo <mistydemeo at gmail.com>
> 
> ---
>  Changelog              |  1 +
>  libavformat/segafilm.c | 24 ++++++++++++++++++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/Changelog b/Changelog
> index 7969b414c4..6b3b2bf7fe 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -47,6 +47,7 @@ version <next>:
>  - native SBC encoder and decoder
>  - drmeter audio filter
>  - hapqa_extract bitstream filter
> +- segafilm: set timestamps when demuxing
>  
>  
>  version 3.4:
> diff --git a/libavformat/segafilm.c b/libavformat/segafilm.c
> index 11768823fc..2295fb3fa5 100644
> --- a/libavformat/segafilm.c
> +++ b/libavformat/segafilm.c
> @@ -270,6 +270,8 @@ static int film_read_packet(AVFormatContext *s,
>      FilmDemuxContext *film = s->priv_data;
>      AVIOContext *pb = s->pb;
>      film_sample *sample;
> +    film_sample *next_sample = NULL;
> +    int next_sample_id;
>      int ret = 0;
>  
>      if (film->current_sample >= film->sample_count)
> @@ -277,6 +279,21 @@ static int film_read_packet(AVFormatContext *s,
>  
>      sample = &film->sample_table[film->current_sample];
>  
> +    /* Find the next sample from the same stream, assuming there is one;
> +     * this is used to calculate the duration below */
> +    next_sample_id = film->current_sample + 1;
> +    while (next_sample == NULL) {
> +        if (next_sample_id >= film->sample_count) {
> +            break;
> +        }
> +
> +        next_sample = &film->sample_table[next_sample_id];
> +        if (next_sample->stream != sample->stream) {
> +            next_sample = NULL;
> +            next_sample_id++;
> +        }
> +    }
> +
>      /* position the stream (will probably be there anyway) */
>      avio_seek(pb, sample->sample_offset, SEEK_SET);
>  
> @@ -287,6 +304,13 @@ static int film_read_packet(AVFormatContext *s,
>      pkt->stream_index = sample->stream;
>      pkt->pts = sample->pts;
>      pkt->flags |= sample->keyframe;

> +    pkt->dts = sample->pts;

this may be redundant


> +    pkt->size = sample->sample_size;

This is not correct, the packet has its size already set, if for some
reason like IO failures its different overriding this could crash the
code later


> +    if (next_sample != NULL) {
> +        pkt->duration = next_sample->pts - sample->pts;
> +    } else {

> +        pkt->duration = 0;
> +    }

setting duration to "nothing"  should not be needed, this should be
already teh default

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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