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author | Derek Buitenhuis <derek.buitenhuis@gmail.com> | 2016-02-16 19:19:23 +0000 |
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committer | Derek Buitenhuis <derek.buitenhuis@gmail.com> | 2016-02-16 19:25:17 +0000 |
commit | 58dd885f9ae7feee002773253e345e11e7142739 (patch) | |
tree | fbc4ca8c9d0367b61a7654b0f479bf528cb04058 /libavcodec/mpeg12.c | |
parent | 8e2105297daecba193ce6f264becd2d5245f2d9d (diff) | |
parent | 7c25ffe070c286874a8c3513f7504b90e1626b0c (diff) | |
download | ffmpeg-streaming-58dd885f9ae7feee002773253e345e11e7142739.zip ffmpeg-streaming-58dd885f9ae7feee002773253e345e11e7142739.tar.gz |
Merge commit '7c25ffe070c286874a8c3513f7504b90e1626b0c'
* commit '7c25ffe070c286874a8c3513f7504b90e1626b0c':
mpeg1: Make intra-block decoding independent of MpegEncContext
Merged-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Diffstat (limited to 'libavcodec/mpeg12.c')
-rw-r--r-- | libavcodec/mpeg12.c | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c index e8a4048..765a80d 100644 --- a/libavcodec/mpeg12.c +++ b/libavcodec/mpeg12.c @@ -243,3 +243,100 @@ int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, return END_NOT_FOUND; } +#define MAX_INDEX (64 - 1) + +int ff_mpeg1_decode_block_intra(GetBitContext *gb, + const uint16_t *quant_matrix, + uint8_t *const scantable, int last_dc[3], + int16_t *block, int index, int qscale, + int block_last_index[12]) +{ + int dc, diff, i = 0, component; + RLTable *rl = &ff_rl_mpeg1; + + /* DC coefficient */ + component = index <= 3 ? 0 : index - 4 + 1; + + diff = decode_dc(gb, component); + if (diff >= 0xffff) + return AVERROR_INVALIDDATA; + + dc = last_dc[component]; + dc += diff; + last_dc[component] = dc; + + block[0] = dc * quant_matrix[0]; + + { + OPEN_READER(re, gb); + UPDATE_CACHE(re, gb); + if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF) + goto end; + + /* now quantify & encode AC coefficients */ + while (1) { + int level, run, j; + + GET_RL_VLC(level, run, re, gb, rl->rl_vlc[0], + TEX_VLC_BITS, 2, 0); + + if (level != 0) { + i += run; + if (i > MAX_INDEX) + break; + + j = scantable[i]; + level = (level * qscale * quant_matrix[j]) >> 4; + level = (level - 1) | 1; + level = (level ^ SHOW_SBITS(re, gb, 1)) - + SHOW_SBITS(re, gb, 1); + SKIP_BITS(re, gb, 1); + } else { + /* escape */ + run = SHOW_UBITS(re, gb, 6) + 1; + LAST_SKIP_BITS(re, gb, 6); + UPDATE_CACHE(re, gb); + level = SHOW_SBITS(re, gb, 8); + SKIP_BITS(re, gb, 8); + + if (level == -128) { + level = SHOW_UBITS(re, gb, 8) - 256; + SKIP_BITS(re, gb, 8); + } else if (level == 0) { + level = SHOW_UBITS(re, gb, 8); + SKIP_BITS(re, gb, 8); + } + + i += run; + if (i > MAX_INDEX) + break; + + j = scantable[i]; + if (level < 0) { + level = -level; + level = (level * qscale * quant_matrix[j]) >> 4; + level = (level - 1) | 1; + level = -level; + } else { + level = (level * qscale * quant_matrix[j]) >> 4; + level = (level - 1) | 1; + } + } + + block[j] = level; + if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF) + break; + + UPDATE_CACHE(re, gb); + } +end: + LAST_SKIP_BITS(re, gb, 2); + CLOSE_READER(re, gb); + } + + if (i > MAX_INDEX) + i = AVERROR_INVALIDDATA; + + block_last_index[index] = i; + return 0; +} |