[FFmpeg-devel] [PATCH 4/4] avcodec/mpeg12enc: Deprecate using MPEG-2 intra VLC table for mpeg1video

[James Almer]

On 11/24/2020 11:41 AM, Andreas Rheinhardt wrote:
> This option just creates broken output because an MPEG-1 bitstream
> can't signal whether MPEG-2 intra VLC tables have been used.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
> Missing version bump.
> 
>   doc/APIchanges         | 3 +++
>   libavcodec/mpeg12enc.c | 7 +++++--
>   2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/APIchanges b/doc/APIchanges
> index b70c78a483..dea54c4415 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,9 @@ libavutil:     2017-10-21
>   
>   API changes, most recent first:
>   
> +2020-xx-xx - xxxxxxxxxx - lavc 58.xx.100 - avcodec.h
> +  Deprecate the "intra_vlc" option for the mpeg1video encoder.

Options usually don't get APIChanges entries, either when they are added 
or removed.

> +
>   2020-xx-xx - xxxxxxxxxx - lavf 58.64.100 - avformat.h
>     Add AVSTREAM_EVENT_FLAG_NEW_PACKETS.
>   
> diff --git a/libavcodec/mpeg12enc.c b/libavcodec/mpeg12enc.c
> index 2466db8a91..0b5badde3c 100644
> --- a/libavcodec/mpeg12enc.c
> +++ b/libavcodec/mpeg12enc.c
> @@ -1114,6 +1114,7 @@ av_cold void ff_mpeg1_encode_init(MpegEncContext *s)
>       if (s->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
>           s->min_qcoeff = -255;
>           s->max_qcoeff = 255;
> +        s->intra_vlc_format = 0;
>       } else {
>           s->min_qcoeff = -2047;
>           s->max_qcoeff = 2047;
> @@ -1136,8 +1137,6 @@ av_cold void ff_mpeg1_encode_init(MpegEncContext *s)
>   #define COMMON_OPTS                                                           \
>       { "gop_timecode",        "MPEG GOP Timecode in hh:mm:ss[:;.]ff format. Overrides timecode_frame_start.",   \
>         OFFSET(tc_opt_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, VE },\
> -    { "intra_vlc",           "Use MPEG-2 intra VLC table.",                   \
> -      OFFSET(intra_vlc_format),    AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE }, \
>       { "drop_frame_timecode", "Timecode is in drop frame format.",             \
>         OFFSET(drop_frame_timecode), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE }, \
>       { "scan_offset",         "Reserve space for SVCD scan offset user data.", \
> @@ -1147,12 +1146,16 @@ av_cold void ff_mpeg1_encode_init(MpegEncContext *s)
>   
>   static const AVOption mpeg1_options[] = {
>       COMMON_OPTS
> +    { "intra_vlc",           "deprecated, does nothing",
> +      OFFSET(intra_vlc_format),    AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE | AV_OPT_FLAG_DEPRECATED },
>       FF_MPV_COMMON_OPTS
>       { NULL },
>   };
>   
>   static const AVOption mpeg2_options[] = {
>       COMMON_OPTS
> +    { "intra_vlc",        "Use MPEG-2 intra VLC table.",
> +      OFFSET(intra_vlc_format),    AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
>       { "non_linear_quant", "Use nonlinear quantizer.",    OFFSET(q_scale_type),   AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
>       { "alternate_scan",   "Enable alternate scantable.", OFFSET(alternate_scan), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
>       { "seq_disp_ext",     "Write sequence_display_extension blocks.", OFFSET(seq_disp_ext), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 1, VE, "seq_disp_ext" },
>