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avcodec/mjpegdec: simplify bayer width handling

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Double s->avctx->width directly, simplifying width-related code in
ljpeg_decode_rgb_scan().
This commit is contained in:
Ramiro Polla 2026-02-13 22:34:13 +01:00
parent 2065ead16e
commit 0ac3b00a18
1 changed files with 18 additions and 23 deletions
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41
libavcodec/mjpegdec.c
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@ -426,19 +426,6 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
return AVERROR_PATCHWELCOME;
}
if (s->bayer) {
if (nb_components == 2) {
/* Bayer images embedded in DNGs can contain 2 interleaved components and the
width stored in their SOF3 markers is the width of each one. We only output
a single component, therefore we need to adjust the output image width. We
handle the deinterleaving (but not the debayering) in this file. */
width *= 2;
}
/* They can also contain 1 component, which is double the width and half the height
of the final image (rows are interleaved). We don't handle the decoding in this
file, but leave that to the TIFF/DNG decoder. */
}
/* if different size, realloc/alloc picture */
if (width != s->width || height != s->height || bits != s->bits ||
memcmp(s->h_count, h_count, sizeof(h_count)) ||
@ -475,6 +462,19 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
s->orig_height < height)
s->avctx->height = AV_CEIL_RSHIFT(s->orig_height, s->avctx->lowres);
if (s->bayer) {
if (nb_components == 2) {
/* Bayer images embedded in DNGs can contain 2 interleaved components and the
* width stored in their SOF3 markers is the width of each one. We only output
* a single component, therefore we need to adjust the output image width. We
* handle the deinterleaving (but not the debayering) in this file. */
s->avctx->width *= 2;
}
/* They can also contain 1 component, which is double the width and half the height
* of the final image (rows are interleaved). We don't handle the decoding in this
* file, but leave that to the TIFF/DNG decoder. */
}
s->first_picture = 0;
} else {
size_change = 0;
@ -1086,7 +1086,6 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s)
int predictor = s->Ss;
int point_transform = s->Al;
int i, mb_x, mb_y;
unsigned width;
uint16_t (*buffer)[4];
int left[4], top[4], topleft[4];
const int linesize = s->linesize[0];
@ -1108,12 +1107,8 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s)
return AVERROR_INVALIDDATA;
}
if (s->bayer)
width = s->mb_width / nb_components; /* Interleaved, width stored is the total so need to divide */
else
width = s->mb_width;
av_fast_malloc(&s->ljpeg_buffer, &s->ljpeg_buffer_size, width * 4 * sizeof(s->ljpeg_buffer[0][0]));
av_fast_malloc(&s->ljpeg_buffer, &s->ljpeg_buffer_size,
(unsigned)s->mb_width * 4 * sizeof(s->ljpeg_buffer[0][0]));
if (!s->ljpeg_buffer)
return AVERROR(ENOMEM);
@ -1133,7 +1128,7 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s)
for (i = 0; i < 4; i++)
top[i] = left[i] = topleft[i] = buffer[0][i];
for (mb_x = 0; mb_x < width; mb_x++) {
for (mb_x = 0; mb_x < s->mb_width; mb_x++) {
int modified_predictor = predictor;
int restart;
@ -1210,10 +1205,10 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s)
return AVERROR_PATCHWELCOME;
if (nb_components == 1) {
/* Leave decoding to the TIFF/DNG decoder (see comment in ff_mjpeg_decode_sof) */
for (mb_x = 0; mb_x < width; mb_x++)
for (mb_x = 0; mb_x < s->mb_width; mb_x++)
((uint16_t*)ptr)[mb_x] = buffer[mb_x][0];
} else if (nb_components == 2) {
for (mb_x = 0; mb_x < width; mb_x++) {
for (mb_x = 0; mb_x < s->mb_width; mb_x++) {
((uint16_t*)ptr)[2 * mb_x + 0] = buffer[mb_x][0];
((uint16_t*)ptr)[2 * mb_x + 1] = buffer[mb_x][1];
}