[FFmpeg-devel] [PATCHv2 2/2] lavc: add support for CODEC_CAP_DELAY in subtitles

[Marton Balint]

On Wed, 23 Oct 2013, Marton Balint wrote:

> This patch adds CODEC_CAP_DELAY support to avcodec_decode_subtitle2.
>
> For DVB teletext decoding, a single teletext packet can contain multiple
> teletext pages. In order to support that, the teletext decoder may buffer
> some pages.
>
> Changes since v1:
> - fixed copypaste errors in docs
> - added packet size check to recode_subtitle
>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> doc/APIchanges       | 3 +++
> libavcodec/avcodec.h | 8 ++++++++
> libavcodec/utils.c   | 4 ++--
> libavcodec/version.h | 2 +-
> 4 files changed, 14 insertions(+), 3 deletions(-)
>

Ping...

Regards,
Marton

> diff --git a/doc/APIchanges b/doc/APIchanges
> index c1f103a..399e8a9 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,9 @@ libavutil:     2012-10-22
>
> API changes, most recent first:
>
> +2013-10-xx - xxxxxxx - lavc 55.39.100 - avcodec.h
> +  Add CODEC_CAP_DELAY support to avcodec_decode_subtitle2.
> +
> libavutil 52.47.100
> 2013-10-17 - xxxxxxx - lavu 52.47.100 - opt.h
>   Add AV_OPT_TYPE_CHANNEL_LAYOUT and channel layout option handlers
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index b9a9f25..ecec55e 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -3894,6 +3894,14 @@ int avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture,
>  * and reusing a get_buffer written for video codecs would probably perform badly
>  * due to a potentially very different allocation pattern.
>  *
> + * Some decoders (those marked with CODEC_CAP_DELAY) have a delay between input
> + * and output. This means that for some packets they will not immediately
> + * produce decoded output and need to be flushed at the end of decoding to get
> + * all the decoded data. Flushing is done by calling this function with packets
> + * with avpkt->data set to NULL and avpkt->size set to 0 until it stops
> + * returning subtitles. It is safe to flush even those decoders that are not
> + * marked with CODEC_CAP_DELAY, then no subtitles will be returned.
> + *
>  * @param avctx the codec context
>  * @param[out] sub The AVSubtitle in which the decoded subtitle will be stored, must be
>                    freed with avsubtitle_free if *got_sub_ptr is set.
> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> index c1625a2..186993d 100644
> --- a/libavcodec/utils.c
> +++ b/libavcodec/utils.c
> @@ -2322,7 +2322,7 @@ static int recode_subtitle(AVCodecContext *avctx,
>     AVPacket tmp;
> #endif
>
> -    if (avctx->sub_charenc_mode != FF_SUB_CHARENC_MODE_PRE_DECODER)
> +    if (avctx->sub_charenc_mode != FF_SUB_CHARENC_MODE_PRE_DECODER || inpkt->size == 0)
>         return 0;
>
> #if CONFIG_ICONV
> @@ -2407,7 +2407,7 @@ int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
>     *got_sub_ptr = 0;
>     avcodec_get_subtitle_defaults(sub);
>
> -    if (avpkt->size) {
> +    if ((avctx->codec->capabilities & CODEC_CAP_DELAY) || avpkt->size) {
>         AVPacket pkt_recoded;
>         AVPacket tmp = *avpkt;
>         int did_split = av_packet_split_side_data(&tmp);
> diff --git a/libavcodec/version.h b/libavcodec/version.h
> index db43b83..7528362 100644
> --- a/libavcodec/version.h
> +++ b/libavcodec/version.h
> @@ -29,7 +29,7 @@
> #include "libavutil/avutil.h"
>
> #define LIBAVCODEC_VERSION_MAJOR 55
> -#define LIBAVCODEC_VERSION_MINOR  38
> +#define LIBAVCODEC_VERSION_MINOR  39
> #define LIBAVCODEC_VERSION_MICRO 100
>
> #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
> -- 
> 1.8.1.4
>
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