[FFmpeg-devel] [PATCH v2 1/2] avformat/movenc: Added an option to disable SIDX atom

[Tobias Rapp]

On 05.12.2018 07:18, Karthick J wrote:
> ---
>   doc/muxers.texi      |  4 ++++
>   libavformat/movenc.c | 12 ++++++++++--
>   libavformat/movenc.h |  1 +
>   3 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index f1cc6f5fee..ca10741900 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -1325,6 +1325,10 @@ more efficient), but with this option set, the muxer writes one moof/mdat
>   pair for each track, making it easier to separate tracks.
>   
>   This option is implicitly set when writing ismv (Smooth Streaming) files.
> + at item -movflags skip_sidx
> +Skip writing of sidx atom. When bitrate overhead due to sidx atom is high,
> +this option could be used for cases where sidx atom is not mandatory.
> +When global_sidx flag is enabled, this option will be ignored.
>   @item -movflags faststart
>   Run a second pass moving the index (moov atom) to the beginning of the file.
>   This operation can take a while, and will not work in various situations such
> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> index 6dab5193b0..3781a32895 100644
> --- a/libavformat/movenc.c
> +++ b/libavformat/movenc.c
> @@ -75,6 +75,7 @@ static const AVOption options[] = {
>       { "frag_discont", "Signal that the next fragment is discontinuous from earlier ones", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_FRAG_DISCONT}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
>       { "delay_moov", "Delay writing the initial moov until the first fragment is cut, or until the first fragment flush", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_DELAY_MOOV}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
>       { "global_sidx", "Write a global sidx index at the start of the file", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_GLOBAL_SIDX}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
> +    { "skip_sidx", "Skip writing of sidx atom", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_SKIP_SIDX}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
>       { "write_colr", "Write colr atom (Experimental, may be renamed or changed, do not use from scripts)", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_WRITE_COLR}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
>       { "write_gama", "Write deprecated gama atom", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_WRITE_GAMA}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
>       { "use_metadata_tags", "Use mdta atom for metadata.", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_USE_MDTA}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
> @@ -4603,7 +4604,8 @@ static int mov_write_moof_tag(AVIOContext *pb, MOVMuxContext *mov, int tracks,
>       mov_write_moof_tag_internal(avio_buf, mov, tracks, 0);
>       moof_size = ffio_close_null_buf(avio_buf);
>   
> -    if (mov->flags & FF_MOV_FLAG_DASH && !(mov->flags & FF_MOV_FLAG_GLOBAL_SIDX))
> +    if (mov->flags & FF_MOV_FLAG_DASH &&
> +        !(mov->flags & (FF_MOV_FLAG_GLOBAL_SIDX | FF_MOV_FLAG_SKIP_SIDX)))
>           mov_write_sidx_tags(pb, mov, tracks, moof_size + 8 + mdat_size);
>   
>       if (mov->write_prft > MOV_PRFT_NONE && mov->write_prft < MOV_PRFT_NB)
> @@ -5422,7 +5424,8 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
>                * the next fragment. This means the cts of the first sample must
>                * be the same in all fragments, unless end_pts was updated by
>                * the packet causing the fragment to be written. */
> -            if ((mov->flags & FF_MOV_FLAG_DASH && !(mov->flags & FF_MOV_FLAG_GLOBAL_SIDX)) ||
> +            if ((mov->flags & FF_MOV_FLAG_DASH &&
> +                !(mov->flags & (FF_MOV_FLAG_GLOBAL_SIDX | FF_MOV_FLAG_SKIP_SIDX))) ||
>                   mov->mode == MODE_ISM)
>                   pkt->pts = pkt->dts + trk->end_pts - trk->cluster[trk->entry].dts;
>           } else {
> @@ -6067,6 +6070,11 @@ static int mov_init(AVFormatContext *s)
>           s->flags &= ~AVFMT_FLAG_AUTO_BSF;
>       }
>   
> +    if (mov->flags & FF_MOV_FLAG_GLOBAL_SIDX && s->flags & FF_MOV_FLAG_SKIP_SIDX) {
> +        av_log(s, AV_LOG_WARNING, "Global SIDX enabled; Ignoring skip_sidx option\n");
> +        s->flags &= ~FF_MOV_FLAG_SKIP_SIDX;
> +    }
> +

I guess this should use mov->flags instead of s->flags?

>       if (mov->flags & FF_MOV_FLAG_FASTSTART) {
>           mov->reserved_moov_size = -1;
>       }
> diff --git a/libavformat/movenc.h b/libavformat/movenc.h
> index fe605d1ad2..68d6f23a5a 100644
> --- a/libavformat/movenc.h
> +++ b/libavformat/movenc.h
> @@ -257,6 +257,7 @@ typedef struct MOVMuxContext {
>   #define FF_MOV_FLAG_SKIP_TRAILER          (1 << 18)
>   #define FF_MOV_FLAG_NEGATIVE_CTS_OFFSETS  (1 << 19)
>   #define FF_MOV_FLAG_FRAG_EVERY_FRAME      (1 << 20)
> +#define FF_MOV_FLAG_SKIP_SIDX             (1 << 21)
>   
>   int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt);
>   
> 

Otherwise changes look fine, but I am not the maintainer of this file.

Regards,
Tobias