Re: [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.rheinha...@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" },


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