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Code Issues Releases Activity

Distinguish between non-coded blocks and decode errors in rtjpeg's get_block

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Originally committed as revision 18926 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Reimar Döffinger
2009-05-24 09:06:06 +00:00
parent 8d857c5434
commit 77336b6127
1 changed files with 10 additions and 9 deletions
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19
libavcodec/rtjpeg.c
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@@ -38,6 +38,7 @@
* \param block where data is written to
* \param scan array containing the mapping stream address -> block position
* \param quant quantization factors
* \return 0 means the block is not coded, < 0 means an error occurred.
*
* Note: GetBitContext is used to make the code simpler, since all data is
* aligned this could be done faster in a different way, e.g. as it is done
@@ -56,7 +57,7 @@ static inline int get_block(GetBitContext *gb, DCTELEM *block, const uint8_t *sc
// number of non-zero coefficients
coeff = get_bits(gb, 6);
if (get_bits_count(gb) + (coeff << 1) >= gb->size_in_bits)
return 0;
return -1;
// normally we would only need to clear the (63 - coeff) last values,
// but since we do not know where they are we just clear the whole block
@@ -73,7 +74,7 @@ static inline int get_block(GetBitContext *gb, DCTELEM *block, const uint8_t *sc
// 4 bits per coefficient
ALIGN(4);
if (get_bits_count(gb) + (coeff << 2) >= gb->size_in_bits)
return 0;
return -1;
while (coeff) {
ac = get_sbits(gb, 4);
if (ac == -8)
@@ -84,7 +85,7 @@ static inline int get_block(GetBitContext *gb, DCTELEM *block, const uint8_t *sc
// 8 bits per coefficient
ALIGN(8);
if (get_bits_count(gb) + (coeff << 3) >= gb->size_in_bits)
return 0;
return -1;
while (coeff) {
ac = get_sbits(gb, 8);
PUT_COEFF(ac);
@@ -114,22 +115,22 @@ int rtjpeg_decode_frame_yuv420(RTJpegContext *c, AVFrame *f,
for (y = 0; y < h; y++) {
for (x = 0; x < w; x++) {
DCTELEM *block = c->block;
if (get_block(&gb, block, c->scan, c->lquant))
if (get_block(&gb, block, c->scan, c->lquant) > 0)
c->dsp->idct_put(y1, f->linesize[0], block);
y1 += 8;
if (get_block(&gb, block, c->scan, c->lquant))
if (get_block(&gb, block, c->scan, c->lquant) > 0)
c->dsp->idct_put(y1, f->linesize[0], block);
y1 += 8;
if (get_block(&gb, block, c->scan, c->lquant))
if (get_block(&gb, block, c->scan, c->lquant) > 0)
c->dsp->idct_put(y2, f->linesize[0], block);
y2 += 8;
if (get_block(&gb, block, c->scan, c->lquant))
if (get_block(&gb, block, c->scan, c->lquant) > 0)
c->dsp->idct_put(y2, f->linesize[0], block);
y2 += 8;
if (get_block(&gb, block, c->scan, c->cquant))
if (get_block(&gb, block, c->scan, c->cquant) > 0)
c->dsp->idct_put(u, f->linesize[1], block);
u += 8;
if (get_block(&gb, block, c->scan, c->cquant))
if (get_block(&gb, block, c->scan, c->cquant) > 0)
c->dsp->idct_put(v, f->linesize[2], block);
v += 8;
}