[FFmpeg-devel] [FFmpeg-cvslog] avcodec/gif: enable encoding single gif image per frame

[Paul B Mahol]

On 12/15/18, Paul B Mahol <onemda at gmail.com> wrote:
> On 12/15/18, Paul B Mahol <onemda at gmail.com> wrote:
>> On 12/15/18, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>>> 2018-12-13 19:32 GMT+01:00, Paul B Mahol <git at videolan.org>:
>>>> ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Wed Dec 12
>>>> 13:19:33 2018 +0100| [bb0984cc29e93e56506722fe0ce5c6d43b6d4326] |
>>>> committer:
>>>> Paul B Mahol
>>>>
>>>> avcodec/gif: enable encoding single gif image per frame
>>>>
>>>> Unbreaks gif image2 muxer.
>>>>
>>>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=bb0984cc29e93e56506722fe0ce5c6d43b6d4326
>>>> ---
>>>>
>>>>  libavcodec/gif.c | 20 ++++++++++++++------
>>>>  1 file changed, 14 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/libavcodec/gif.c b/libavcodec/gif.c
>>>> index 408b7534da..67fc5a1bda 100644
>>>> --- a/libavcodec/gif.c
>>>> +++ b/libavcodec/gif.c
>>>> @@ -51,6 +51,7 @@ typedef struct GIFContext {
>>>>      int is_first_frame;
>>>>      AVFrame *last_frame;
>>>>      int flags;
>>>> +    int image;
>>>>      uint32_t palette[AVPALETTE_COUNT];  ///< local reference palette
>>>> for
>>>> !pal8
>>>>      int palette_loaded;
>>>>      int transparent_index;
>>>> @@ -422,6 +423,9 @@ static int gif_encode_frame(AVCodecContext *avctx,
>>>> AVPacket *pkt,
>>>>      outbuf_ptr = pkt->data;
>>>>      end        = pkt->data + pkt->size;
>>>>
>>>> +    if (s->image)
>>>> +        s->is_first_frame = 1;
>>>> +
>>>>      if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
>>>>          palette = (uint32_t*)pict->data[1];
>>>>
>>>> @@ -436,19 +440,22 @@ static int gif_encode_frame(AVCodecContext
>>>> *avctx,
>>>> AVPacket *pkt,
>>>>
>>>>      gif_image_write_image(avctx, &outbuf_ptr, end, palette,
>>>>                            pict->data[0], pict->linesize[0], pkt);
>>>> -    if (!s->last_frame) {
>>>> +    if (!s->last_frame && !s->image) {
>>>>          s->last_frame = av_frame_alloc();
>>>>          if (!s->last_frame)
>>>>              return AVERROR(ENOMEM);
>>>>      }
>>>>
>>>> -    av_frame_unref(s->last_frame);
>>>> -    ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
>>>> -    if (ret < 0)
>>>> -        return ret;
>>>> +    if (!s->image) {
>>>> +        av_frame_unref(s->last_frame);
>>>> +        ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
>>>> +        if (ret < 0)
>>>> +            return ret;
>>>> +    }
>>>>
>>>>      pkt->size   = outbuf_ptr - pkt->data;
>>>> -    pkt->flags |= AV_PKT_FLAG_KEY;
>>>> +    if (s->is_first_frame)
>>>> +        pkt->flags |= AV_PKT_FLAG_KEY;
>>>>      *got_packet = 1;
>>>>
>>>>      return 0;
>>>> @@ -472,6 +479,7 @@ static const AVOption gif_options[] = {
>>>>      { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS,
>>>> {.i64
>>>> = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
>>>>          { "offsetting", "enable picture offsetting", 0,
>>>> AV_OPT_TYPE_CONST,
>>>> {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
>>>>          { "transdiff", "enable transparency detection between frames",
>>>> 0,
>>>> AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS,
>>>> "flags"
>>>> },
>>>> +    { "gifimage", "enable encoding only images per frame",
>>>> OFFSET(image),
>>>> AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS, "flags" },
>>>
>>> Would it not be possible to detect in the flush function that only one
>>> frame
>>> was encoded and make the flag unnecessary?
>>
>> Unfortunately not, gif encoder is not reset anywhere and so
>> frame_number is never set back to 0.
>>
>
> I could use par->codec_tag for this 'GIFI' for images, image2 muxer
> would set this, and encoder could check it, but this is far from
> perfect solution.
>

Or create fake extradata.