[FFmpeg-devel] [PATCH v2 087/162] avcodec/mpeg4videodec: Make studio VLCs static

[Andreas Rheinhardt]

Michael Niedermayer:
> On Fri, Nov 20, 2020 at 08:20:00AM +0100, Andreas Rheinhardt wrote:
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>>  libavcodec/mpeg4video.h    |  4 --
>>  libavcodec/mpeg4videodec.c | 88 ++++++++++++++++----------------------
>>  2 files changed, 36 insertions(+), 56 deletions(-)
>>
>> diff --git a/libavcodec/mpeg4video.h b/libavcodec/mpeg4video.h
>> index 3de598465f..e919db87a5 100644
>> --- a/libavcodec/mpeg4video.h
>> +++ b/libavcodec/mpeg4video.h
>> @@ -115,10 +115,6 @@ typedef struct Mpeg4DecContext {
>>      int cplx_estimation_trash_p;
>>      int cplx_estimation_trash_b;
>>  
>> -    VLC studio_intra_tab[12];
>> -    VLC studio_luma_dc;
>> -    VLC studio_chroma_dc;
>> -
>>      int rgb;
>>  } Mpeg4DecContext;
>>  
>> diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
>> index cc3c36d722..19dcaff764 100644
>> --- a/libavcodec/mpeg4videodec.c
>> +++ b/libavcodec/mpeg4videodec.c
>> @@ -25,6 +25,7 @@
>>  #include "libavutil/internal.h"
>>  #include "libavutil/opt.h"
>>  #include "libavutil/pixdesc.h"
>> +#include "libavutil/thread.h"
>>  #include "error_resilience.h"
>>  #include "hwconfig.h"
>>  #include "idctdsp.h"
>> @@ -53,6 +54,9 @@ static int decode_studio_vol_header(Mpeg4DecContext *ctx, GetBitContext *gb);
>>  static VLC dc_lum, dc_chrom;
>>  static VLC sprite_trajectory;
>>  static VLC mb_type_b_vlc;
>> +static VLC studio_intra_tab[12];
>> +static VLC studio_luma_dc;
>> +static VLC studio_chroma_dc;
>>  
>>  static const int mb_type_b_map[4] = {
>>      MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
>> @@ -1820,7 +1824,7 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
>>  
>>      int cc, dct_dc_size, dct_diff, code, j, idx = 1, group = 0, run = 0,
>>          additional_code_len, sign, mismatch;
>> -    VLC *cur_vlc = &ctx->studio_intra_tab[0];
>> +    const VLC *cur_vlc = &studio_intra_tab[0];
>>      uint8_t *const scantable = s->intra_scantable.permutated;
>>      const uint16_t *quant_matrix;
>>      uint32_t flc;
>> @@ -1834,14 +1838,14 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
>>  
>>      if (n < 4) {
>>          cc = 0;
>> -        dct_dc_size = get_vlc2(&s->gb, ctx->studio_luma_dc.table, STUDIO_INTRA_BITS, 2);
>> +        dct_dc_size = get_vlc2(&s->gb, studio_luma_dc.table, STUDIO_INTRA_BITS, 2);
>>          quant_matrix = s->intra_matrix;
>>      } else {
>>          cc = (n & 1) + 1;
>>          if (ctx->rgb)
>> -            dct_dc_size = get_vlc2(&s->gb, ctx->studio_luma_dc.table, STUDIO_INTRA_BITS, 2);
>> +            dct_dc_size = get_vlc2(&s->gb, studio_luma_dc.table, STUDIO_INTRA_BITS, 2);
>>          else
>> -            dct_dc_size = get_vlc2(&s->gb, ctx->studio_chroma_dc.table, STUDIO_INTRA_BITS, 2);
>> +            dct_dc_size = get_vlc2(&s->gb, studio_chroma_dc.table, STUDIO_INTRA_BITS, 2);
>>          quant_matrix = s->chroma_intra_matrix;
>>      }
>>  
>> @@ -1878,7 +1882,7 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
>>          }
>>  
>>          additional_code_len = ac_state_tab[group][0];
>> -        cur_vlc = &ctx->studio_intra_tab[ac_state_tab[group][1]];
>> +        cur_vlc = &studio_intra_tab[ac_state_tab[group][1]];
>>  
>>          if (group == 0) {
>>              /* End of Block */
>> @@ -3501,40 +3505,36 @@ static int mpeg4_update_thread_context(AVCodecContext *dst,
>>  }
>>  #endif
>>  
>> -static av_cold int init_studio_vlcs(Mpeg4DecContext *ctx)
>> +static av_cold void mpeg4_init_static(void)
>>  {
>> -    int i, ret;
>> -
>> -    for (i = 0; i < 12; i++) {
>> -        ret = ff_init_vlc_from_lengths(&ctx->studio_intra_tab[i],
>> -                                       STUDIO_INTRA_BITS, 24,
>> -                                       &ff_mpeg4_studio_intra[i][0][1], 2,
>> -                                       &ff_mpeg4_studio_intra[i][0][0], 2, 1,
>> -                                       0, 0, NULL);
>> -
>> -        if (ret < 0)
>> -            return ret;
>> +    INIT_VLC_STATIC_FROM_LENGTHS(&studio_luma_dc, STUDIO_INTRA_BITS, 19,
>> +                                 &ff_mpeg4_studio_dc_luma[0][1], 2,
>> +                                 &ff_mpeg4_studio_dc_luma[0][0], 2, 1,
>> +                                 0, 0, 528);
>> +
>> +    INIT_VLC_STATIC_FROM_LENGTHS(&studio_chroma_dc, STUDIO_INTRA_BITS, 19,
>> +                                 &ff_mpeg4_studio_dc_chroma[0][1], 2,
>> +                                 &ff_mpeg4_studio_dc_chroma[0][0], 2, 1,
>> +                                 0, 0, 528);
>> +
> 
>> +    for (unsigned i = 0, offset = 0; i < 12; i++) {
> 
> why unsigned ?
> its a bit unexpected for "i"
> 

Because all the numbers here are nonnegative. But I can change it if it
is surprising.
(For me, "i" is not an abbreviation of "int", but of "index".)

- Andreas