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Code Issues Releases Activity

avcodec/mpegvideo: Move dct_precision to Mpeg4DecContext

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Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-06-19 19:17:28 +02:00
parent 758c8dffc9
commit 3f5c2043cc
3 changed files with 15 additions and 12 deletions
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25
libavcodec/mpeg4videodec.c
View File

@ -787,12 +787,13 @@ int ff_mpeg4_decode_video_packet_header(MPVContext *const s)
return 0;
}
static void reset_studio_dc_predictors(MpegEncContext *s)
static void reset_studio_dc_predictors(Mpeg4DecContext *const ctx)
{
MPVContext *const s = &ctx->m;
/* Reset DC Predictors */
s->last_dc[0] =
s->last_dc[1] =
s->last_dc[2] = 1 << (s->avctx->bits_per_raw_sample + s->dct_precision + s->intra_dc_precision - 1);
s->last_dc[2] = 1 << (s->avctx->bits_per_raw_sample + ctx->dct_precision + s->intra_dc_precision - 1);
}
/**
@ -827,7 +828,7 @@ int ff_mpeg4_decode_studio_slice_header(MPVContext *const s)
skip_bits(gb, 8); /* extra_information_slice */
}
reset_studio_dc_predictors(s);
reset_studio_dc_predictors(ctx);
}
else {
return AVERROR_INVALIDDATA;
@ -2160,7 +2161,7 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
uint32_t flc;
const int min = -1 * (1 << (s->avctx->bits_per_raw_sample + 6));
const int max = ((1 << (s->avctx->bits_per_raw_sample + 6)) - 1);
int shift = 3 - s->dct_precision;
int shift = 3 - ctx->dct_precision;
mismatch = 1;
@ -2196,7 +2197,7 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
if (ctx->mpeg_quant)
block[0] = s->last_dc[cc] * (8 >> s->intra_dc_precision);
else
block[0] = s->last_dc[cc] * (8 >> s->intra_dc_precision) * (8 >> s->dct_precision);
block[0] = s->last_dc[cc] * (8 >> s->intra_dc_precision) * (8 >> ctx->dct_precision);
/* TODO: support mpeg_quant for AC coefficients */
block[0] = av_clip(block[0], min, max);
@ -2246,7 +2247,7 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
if (idx > 63)
return AVERROR_INVALIDDATA;
j = scantable[idx++];
additional_code_len = s->avctx->bits_per_raw_sample + s->dct_precision + 4;
additional_code_len = s->avctx->bits_per_raw_sample + ctx->dct_precision + 4;
flc = get_bits(&s->gb, additional_code_len);
if (flc >> (additional_code_len-1))
block[j] = -1 * (( flc ^ ((1 << additional_code_len) -1)) + 1);
@ -2263,8 +2264,10 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
return 0;
}
static int mpeg4_decode_dpcm_macroblock(MpegEncContext *s, int16_t macroblock[256], int n)
static int mpeg4_decode_dpcm_macroblock(Mpeg4DecContext *const ctx,
int16_t macroblock[256], int n)
{
MPVContext *const s = &ctx->m;
int i, j, w, h, idx = 0;
int block_mean, rice_parameter, rice_prefix_code, rice_suffix_code,
dpcm_residual, left, top, topleft, min_left_top, max_left_top, p, p2, output;
@ -2276,7 +2279,7 @@ static int mpeg4_decode_dpcm_macroblock(MpegEncContext *s, int16_t macroblock[25
av_log(s->avctx, AV_LOG_ERROR, "Forbidden block_mean\n");
return AVERROR_INVALIDDATA;
}
s->last_dc[n] = block_mean * (1 << (s->dct_precision + s->intra_dc_precision));
s->last_dc[n] = block_mean * (1 << (ctx->dct_precision + s->intra_dc_precision));
rice_parameter = get_bits(&s->gb, 4);
if (rice_parameter == 0) {
@ -2373,7 +2376,7 @@ static int mpeg4_decode_studio_mb(MpegEncContext *s, int16_t block_[12][64])
check_marker(s->avctx, &s->gb, "DPCM block start");
ctx->dpcm_direction = get_bits1(&s->gb) ? -1 : 1;
for (i = 0; i < 3; i++) {
if (mpeg4_decode_dpcm_macroblock(s, ctx->dpcm_macroblock[i], i) < 0)
if (mpeg4_decode_dpcm_macroblock(ctx, ctx->dpcm_macroblock[i], i) < 0)
return AVERROR_INVALIDDATA;
}
}
@ -3521,13 +3524,13 @@ static int decode_studio_vop_header(Mpeg4DecContext *ctx, GetBitContext *gb)
if (s->pict_type == AV_PICTURE_TYPE_I) {
if (get_bits1(gb))
reset_studio_dc_predictors(s);
reset_studio_dc_predictors(ctx);
}
if (ctx->shape != BIN_ONLY_SHAPE) {
s->alternate_scan = get_bits1(gb);
s->frame_pred_frame_dct = get_bits1(gb);
s->dct_precision = get_bits(gb, 2);
ctx->dct_precision = get_bits(gb, 2);
s->intra_dc_precision = get_bits(gb, 2);
s->q_scale_type = get_bits1(gb);
}

1
libavcodec/mpeg4videodec.h
View File

@ -105,6 +105,7 @@ typedef struct Mpeg4DecContext {
};
// 0 = DCT, 1 = DPCM top to bottom scan, -1 = DPCM bottom to top scan
int dpcm_direction;
int dct_precision;
} Mpeg4DecContext;
int ff_mpeg4_decode_picture_header(MpegEncContext *s);

1
libavcodec/mpegvideo.h
View File

@ -238,7 +238,6 @@ typedef struct MpegEncContext {
/* MPEG-4 specific */
int studio_profile;
int dct_precision;
int last_time_base;
int time_base; ///< time in seconds of last I,P,S Frame
int64_t time; ///< time of current frame