[FFmpeg-devel] [PATCH] libavdevice/lavfi.c: adjust subcc_packet->pts to be in 90 timebase

[Michael Niedermayer]

On Fri, Sep 30, 2016 at 11:02:32PM -0400, Chris Landry wrote:
> From: Chris Landry <topher.p.landry at gmail.com>
> 
> When a video stream timebase is not 90k, the cc packet pts is relevant to the timebase of the video stream, but later is assumed to be 90k. Adjust it here to be 90k so timing is accurate in resulting subs.
> 
> Signed-off-by: Chris Landry <topher.p.landry at gmail.com>
> ---
>  libavdevice/lavfi.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/libavdevice/lavfi.c b/libavdevice/lavfi.c
> index f9b2694..ffe5e0e 100644
> --- a/libavdevice/lavfi.c
> +++ b/libavdevice/lavfi.c
> @@ -58,6 +58,7 @@ typedef struct {
>      AVFrame *decoded_frame;
>      int nb_sinks;
>      AVPacket subcc_packet;
> +    AVRational video_time_base;
>  } LavfiContext;
>  
>  static int *create_all_formats(int n)
> @@ -317,6 +318,8 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>          st->codecpar->codec_type = link->type;
>          avpriv_set_pts_info(st, 64, link->time_base.num, link->time_base.den);
>          if (link->type == AVMEDIA_TYPE_VIDEO) {
> +            lavfi->video_time_base = link->time_base;
> +
>              st->codecpar->codec_id   = AV_CODEC_ID_RAWVIDEO;
>              st->codecpar->format     = link->format;
>              st->codecpar->width      = link->w;
> @@ -373,8 +376,14 @@ static int create_subcc_packet(AVFormatContext *avctx, AVFrame *frame,
>      if ((ret = av_new_packet(&lavfi->subcc_packet, sd->size)) < 0)
>          return ret;
>      memcpy(lavfi->subcc_packet.data, sd->data, sd->size);
> +
> +    AVRational time_base = lavfi->video_time_base;

likely triggers compiler warning


> +
> +    double adjust_factor = time_base.den / (90000.0 * time_base.num);

floating point is not needed and not ok due to binary non portability
theres av_rescale*

also this breaks make fate

do you have a testcase that this fixes ?

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Freedom in capitalist society always remains about the same as it was in
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