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avcodec/svq1dec: detect buggy FFmpeg encoder and apply correction to interframe mean symbols

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The FFmpeg encoder does not increment the temporal reference field, so use
that knowledge plus the extradata field to detect buggy versions of the encoder.
This commit is contained in:
Peter Ross 2022-11-01 09:24:29 +11:00
parent 6fe8556a19
commit 16af424bf9
1 changed files with 23 additions and 9 deletions
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32
libavcodec/svq1dec.c
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@ -73,6 +73,8 @@ typedef struct SVQ1Context {
int height; int height;
int frame_code; int frame_code;
int nonref; // 1 if the current frame won't be referenced int nonref; // 1 if the current frame won't be referenced
int last_tempref;
} SVQ1Context; } SVQ1Context;
static const uint8_t string_table[256] = { static const uint8_t string_table[256] = {
@ -229,7 +231,7 @@ static int svq1_decode_block_intra(GetBitContext *bitbuf, uint8_t *pixels,
} }
static int svq1_decode_block_non_intra(GetBitContext *bitbuf, uint8_t *pixels, static int svq1_decode_block_non_intra(GetBitContext *bitbuf, uint8_t *pixels,
ptrdiff_t pitch) ptrdiff_t pitch, int buggy)
{ {
uint32_t bit_cache; uint32_t bit_cache;
uint8_t *list[63]; uint8_t *list[63];
@ -270,6 +272,13 @@ static int svq1_decode_block_non_intra(GetBitContext *bitbuf, uint8_t *pixels,
mean = get_vlc2(bitbuf, svq1_inter_mean.table, 9, 3) - 256; mean = get_vlc2(bitbuf, svq1_inter_mean.table, 9, 3) - 256;
if (buggy) {
if (mean == -128)
mean = 128;
else if (mean == 128)
mean = -128;
}
SVQ1_CALC_CODEBOOK_ENTRIES(ff_svq1_inter_codebooks); SVQ1_CALC_CODEBOOK_ENTRIES(ff_svq1_inter_codebooks);
for (y = 0; y < height; y++) { for (y = 0; y < height; y++) {
@ -455,7 +464,7 @@ static int svq1_decode_delta_block(AVCodecContext *avctx, HpelDSPContext *hdsp,
GetBitContext *bitbuf, GetBitContext *bitbuf,
uint8_t *current, uint8_t *previous, uint8_t *current, uint8_t *previous,
ptrdiff_t pitch, svq1_pmv *motion, int x, int y, ptrdiff_t pitch, svq1_pmv *motion, int x, int y,
int width, int height) int width, int height, int buggy)
{ {
uint32_t block_type; uint32_t block_type;
int result = 0; int result = 0;
@ -487,7 +496,7 @@ static int svq1_decode_delta_block(AVCodecContext *avctx, HpelDSPContext *hdsp,
ff_dlog(avctx, "Error in svq1_motion_inter_block %i\n", result); ff_dlog(avctx, "Error in svq1_motion_inter_block %i\n", result);
break; break;
} }
result = svq1_decode_block_non_intra(bitbuf, current, pitch); result = svq1_decode_block_non_intra(bitbuf, current, pitch, buggy);
break; break;
case SVQ1_BLOCK_INTER_4V: case SVQ1_BLOCK_INTER_4V:
@ -498,7 +507,7 @@ static int svq1_decode_delta_block(AVCodecContext *avctx, HpelDSPContext *hdsp,
ff_dlog(avctx, "Error in svq1_motion_inter_4v_block %i\n", result); ff_dlog(avctx, "Error in svq1_motion_inter_4v_block %i\n", result);
break; break;
} }
result = svq1_decode_block_non_intra(bitbuf, current, pitch); result = svq1_decode_block_non_intra(bitbuf, current, pitch, buggy);
break; break;
case SVQ1_BLOCK_INTRA: case SVQ1_BLOCK_INTRA:
@ -524,15 +533,18 @@ static void svq1_parse_string(GetBitContext *bitbuf, uint8_t out[257])
out[i] = 0; out[i] = 0;
} }
static int svq1_decode_frame_header(AVCodecContext *avctx, AVFrame *frame) static int svq1_decode_frame_header(AVCodecContext *avctx, AVFrame *frame, int * buggy)
{ {
SVQ1Context *s = avctx->priv_data; SVQ1Context *s = avctx->priv_data;
GetBitContext *bitbuf = &s->gb; GetBitContext *bitbuf = &s->gb;
int frame_size_code; int frame_size_code;
int width = s->width; int width = s->width;
int height = s->height; int height = s->height;
int tempref;
skip_bits(bitbuf, 8); /* temporal_reference */ tempref = get_bits(bitbuf, 8); /* temporal_reference */
*buggy = tempref == 0 && s->last_tempref == 0 && avctx->extradata_size == 0;
s->last_tempref = tempref;
/* frame type */ /* frame type */
s->nonref = 0; s->nonref = 0;
@ -624,7 +636,7 @@ static int svq1_decode_frame(AVCodecContext *avctx, AVFrame *cur,
int buf_size = avpkt->size; int buf_size = avpkt->size;
SVQ1Context *s = avctx->priv_data; SVQ1Context *s = avctx->priv_data;
uint8_t *current; uint8_t *current;
int result, i, x, y, width, height; int result, i, x, y, width, height, buggy;
int ret; int ret;
/* initialize bit buffer */ /* initialize bit buffer */
@ -664,7 +676,7 @@ static int svq1_decode_frame(AVCodecContext *avctx, AVFrame *cur,
src[i] = ((src[i] << 16) | (src[i] >> 16)) ^ src[7 - i]; src[i] = ((src[i] << 16) | (src[i] >> 16)) ^ src[7 - i];
} }
result = svq1_decode_frame_header(avctx, cur); result = svq1_decode_frame_header(avctx, cur, &buggy);
if (result != 0) { if (result != 0) {
ff_dlog(avctx, "Error in svq1_decode_frame_header %i\n", result); ff_dlog(avctx, "Error in svq1_decode_frame_header %i\n", result);
return result; return result;
@ -734,7 +746,7 @@ static int svq1_decode_frame(AVCodecContext *avctx, AVFrame *cur,
result = svq1_decode_delta_block(avctx, &s->hdsp, result = svq1_decode_delta_block(avctx, &s->hdsp,
&s->gb, &current[x], &s->gb, &current[x],
previous, linesize, previous, linesize,
s->pmv, x, y, width, height); s->pmv, x, y, width, height, buggy);
if (result != 0) { if (result != 0) {
ff_dlog(avctx, ff_dlog(avctx,
"Error in svq1_decode_delta_block %i\n", "Error in svq1_decode_delta_block %i\n",
@ -820,6 +832,8 @@ static av_cold int svq1_decode_init(AVCodecContext *avctx)
ff_thread_once(&init_static_once, svq1_static_init); ff_thread_once(&init_static_once, svq1_static_init);
s->last_tempref = 0xFF;
return 0; return 0;
} }