[FFmpeg-devel] [PATCH] lavc: add duration field to AVFrame

[Michael Niedermayer]

On Thu, Sep 13, 2012 at 11:36:23AM +0200, Stefano Sabatini wrote:
> On date Tuesday 2012-09-11 22:45:33 +0200, Stefano Sabatini encoded:
> > On date Tuesday 2012-09-04 14:13:07 +0200, Stefano Sabatini encoded:
> > > On date Sunday 2012-08-26 05:22:39 +0200, Michael Niedermayer encoded:
> > > > On Thu, Aug 02, 2012 at 05:32:23PM +0200, Stefano Sabatini wrote:
> > > > > On date Thursday 2012-08-02 12:17:48 +0200, Stefano Sabatini encoded:
> > > > >  avcodec.h |   12 ++++++++++++
> > > > >  utils.c   |    5 +++++
> > > > >  2 files changed, 17 insertions(+)
> > > > > 91ac00288f8063d65db98fed503f2c73850956a6  0006-lavc-add-duration-field-to-AVFrame.patch
> > > > > From dffa5ba28c9c9d9510bcfbe8bcb576e895e59c2e Mon Sep 17 00:00:00 2001
> > > > > From: Stefano Sabatini <stefasab at gmail.com>
> > > > > Date: Thu, 2 Aug 2012 13:12:28 +0200
> > > > > Subject: [PATCH] lavc: add duration field to AVFrame
> > > > 
> > > > LGTM
> > > 
> > > The main problem I see with this patch, is that the
> > > avcodec_decode_video2() can't set this value in a sane value (assuming
> > > pkt_duration if not specified and rescaling), since the pkt/stream
> > > time base is not known at the decoder level.
> > > 
> > > With audio this is not a problem, since we can deduce the frame
> > > duration from the number of samples.
> > > 
> > > As a consequence, if frame.duration is not set by the video decoder,
> > > the only possible way to set it, it is to do that at the application
> > > level, which I'd like to avoid.
> > > 
> > > Other possible solutions:
> > 
> 
> > > - set the stream/packet timebase in the decoder context
> 
> This is already implemented.
> 
> Patch updated.
> -- 
> FFmpeg = Funny and Furious Mind-dumbing Pitiless Elastic Generator

>  avcodec.h |   12 ++++++++++++
>  utils.c   |    8 ++++++++
>  2 files changed, 20 insertions(+)
> 42cb2b67000ca9131d16eaedf038e031fe16ab92  0001-lavc-add-duration-field-to-AVFrame.patch
> From 1d46af61ba85e5c7e1cf77e11975205ab42b5477 Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Thu, 2 Aug 2012 13:12:28 +0200
> Subject: [PATCH] lavc: add duration field to AVFrame
> 
> The new field must be set by the decoder, *or* will be set by the
> decoding framework based on the duration value stored in the packet (for
> video) or on the number of audio samples (for audio).
> ---
>  libavcodec/avcodec.h |   12 ++++++++++++
>  libavcodec/utils.c   |    8 ++++++++
>  2 files changed, 20 insertions(+), 0 deletions(-)
> 
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index ddf785e..7da05b8 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -1404,6 +1404,16 @@ typedef struct AVFrame {
>       * - decoding: Read by user.
>       */
>      int64_t channels;
> +
> +    /**
> +     * duration of the frame, expressed in
> +     * AVCodecContext->time_base units, AV_NOPTS_VALUE if unknown.
> +     * Code outside libavcodec should access this field using:
> +     * av_frame_get_duration(frame)
> +     * - encoding: unused
> +     * - decoding: Read by user.
> +     */
> +    int64_t duration;
>  } AVFrame;

the relation to repeat_pict should be clarified ideally


[...]
> @@ -1527,6 +1530,9 @@ int attribute_align_arg avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
>                  picture->height = avctx->height;
>              if (picture->format == PIX_FMT_NONE)
>                  picture->format = avctx->pix_fmt;
> +            if (picture->duration == AV_NOPTS_VALUE && avpkt->duration)
> +                picture->duration = av_rescale_q(avpkt->duration, avctx->pkt_timebase,
> +                                                 avctx->time_base);
>          }
>  
>          emms_c(); //needed to avoid an emms_c() call before every return;

this looks wrong in case of B frames / frame reordering

[...]


-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20121002/96096213/attachment.asc>