[FFmpeg-devel] [PATCH] mjpegdec: Fill raw huffman tables with default values too

[Mark Thompson]

On 13/11/18 00:24, mypopy at gmail.com wrote:
> On Mon, Nov 12, 2018 at 12:26 AM Mark Thompson <sw at jkqxz.net> wrote:
>>
>> These may be used by hwaccel decoders when the standard tables are not
>> otherwise available.  At the same time, clean up that code into an array
>> so it's a little less repetitive.
>> ---
>>  libavcodec/mjpegdec.c | 67 +++++++++++++++++++++++++------------------
>>  1 file changed, 39 insertions(+), 28 deletions(-)
>>
>> diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
>> index 96c425515a..2f1635838a 100644
>> --- a/libavcodec/mjpegdec.c
>> +++ b/libavcodec/mjpegdec.c
>> @@ -73,34 +73,45 @@ static int build_vlc(VLC *vlc, const uint8_t *bits_table,
>>                                huff_code, 2, 2, huff_sym, 2, 2, use_static);
>>  }
>>
>> -static int build_basic_mjpeg_vlc(MJpegDecodeContext *s)
>> +static int init_default_huffman_tables(MJpegDecodeContext *s)
>>  {
>> -    int ret;
>> -
>> -    if ((ret = build_vlc(&s->vlcs[0][0], avpriv_mjpeg_bits_dc_luminance,
>> -                         avpriv_mjpeg_val_dc, 12, 0, 0)) < 0)
>> -        return ret;
>> -
>> -    if ((ret = build_vlc(&s->vlcs[0][1], avpriv_mjpeg_bits_dc_chrominance,
>> -                         avpriv_mjpeg_val_dc, 12, 0, 0)) < 0)
>> -        return ret;
>> -
>> -    if ((ret = build_vlc(&s->vlcs[1][0], avpriv_mjpeg_bits_ac_luminance,
>> -                         avpriv_mjpeg_val_ac_luminance, 251, 0, 1)) < 0)
>> -        return ret;
>> -
>> -    if ((ret = build_vlc(&s->vlcs[1][1], avpriv_mjpeg_bits_ac_chrominance,
>> -                         avpriv_mjpeg_val_ac_chrominance, 251, 0, 1)) < 0)
>> -        return ret;
>> -
>> -    if ((ret = build_vlc(&s->vlcs[2][0], avpriv_mjpeg_bits_ac_luminance,
>> -                         avpriv_mjpeg_val_ac_luminance, 251, 0, 0)) < 0)
>> -        return ret;
>> -
>> -    if ((ret = build_vlc(&s->vlcs[2][1], avpriv_mjpeg_bits_ac_chrominance,
>> -                         avpriv_mjpeg_val_ac_chrominance, 251, 0, 0)) < 0)
>> -        return ret;
>> +    static const struct {
>> +        int class;
>> +        int index;
>> +        const uint8_t *bits;
>> +        const uint8_t *values;
>> +        int codes;
>> +        int length;
>> +    } ht[] = {
>> +        { 0, 0, avpriv_mjpeg_bits_dc_luminance,
>> +                avpriv_mjpeg_val_dc, 12, 12 },
>> +        { 0, 1, avpriv_mjpeg_bits_dc_chrominance,
>> +                avpriv_mjpeg_val_dc, 12, 12 },
>> +        { 1, 0, avpriv_mjpeg_bits_ac_luminance,
>> +                avpriv_mjpeg_val_ac_luminance,   251, 162 },
>> +        { 1, 1, avpriv_mjpeg_bits_ac_chrominance,
>> +                avpriv_mjpeg_val_ac_chrominance, 251, 162 },
>> +        { 2, 0, avpriv_mjpeg_bits_ac_luminance,
>> +                avpriv_mjpeg_val_ac_luminance,   251, 162 },
>> +        { 2, 1, avpriv_mjpeg_bits_ac_chrominance,
>> +                avpriv_mjpeg_val_ac_chrominance, 251, 162 },
>> +    };
>> +    int i, ret;
>> +
>> +    for (i = 0; i < FF_ARRAY_ELEMS(ht); i++) {
>> +        ret = build_vlc(&s->vlcs[ht[i].class][ht[i].index],
>> +                        ht[i].bits, ht[i].values, ht[i].codes,
>> +                        0, ht[i].class == 1);
>> +        if (ret < 0)
>> +            return ret;
>>
>> +        if (ht[i].class < 2) {
>> +            memcpy(s->raw_huffman_lengths[ht[i].class][ht[i].index],
>> +                   ht[i].bits + 1, 16);
>> +            memcpy(s->raw_huffman_values[ht[i].class][ht[i].index],
>> +                   ht[i].values, ht[i].length);
>> +        }
>> +    }
>>
>>      return 0;
>>  }
>> @@ -151,7 +162,7 @@ av_cold int ff_mjpeg_decode_init(AVCodecContext *avctx)
>>      avctx->colorspace = AVCOL_SPC_BT470BG;
>>      s->hwaccel_pix_fmt = s->hwaccel_sw_pix_fmt = AV_PIX_FMT_NONE;
>>
>> -    if ((ret = build_basic_mjpeg_vlc(s)) < 0)
>> +    if ((ret = init_default_huffman_tables(s)) < 0)
>>          return ret;
>>
>>      if (s->extern_huff) {
>> @@ -161,7 +172,7 @@ av_cold int ff_mjpeg_decode_init(AVCodecContext *avctx)
>>          if (ff_mjpeg_decode_dht(s)) {
>>              av_log(avctx, AV_LOG_ERROR,
>>                     "error using external huffman table, switching back to internal\n");
>> -            build_basic_mjpeg_vlc(s);
>> +            init_default_huffman_tables(s);
>>          }
>>      }
>>      if (avctx->field_order == AV_FIELD_BB) { /* quicktime icefloe 019 */
>> --
>> 2.19.1
> LGTM

Applied.

Thanks,

- Mark