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lavc/mjpegdec: Enable decoding of single-component bayer images

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Also, ensure no false positives when determining DNG bayer images, by
setting them in tiff.c instead of relying on a heuristic.  There's no
way to determine this just from the JPEG data, so we have to pass this
information from outside the MJPEG decoder.

Signed-off-by: Nick Renieris <velocityra@gmail.com>
This commit is contained in:
Nick Renieris 2019-08-29 16:10:48 +03:00 committed by Paul B Mahol
parent c510ed2ee8
commit a75a9e8f64
2 changed files with 28 additions and 11 deletions
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32
libavcodec/mjpegdec.c
View File

@ -412,13 +412,17 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
return AVERROR_PATCHWELCOME;
}
/* Lossless JPEGs encoded in DNGs are commonly bayer-encoded. They 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. */
if (s->lossless == 1 && nb_components == 2) {
s->bayer = 1;
width *= 2;
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 */
@ -1184,10 +1188,16 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s, int nb_components, int p
ptr[3*mb_x + 0] = buffer[mb_x][1] + ptr[3*mb_x + 1];
ptr[3*mb_x + 2] = buffer[mb_x][2] + ptr[3*mb_x + 1];
}
} else if (s->bayer && nb_components == 2) {
for (mb_x = 0; mb_x < 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];
} else if (s->bayer) {
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++)
((uint16_t*)ptr)[mb_x] = buffer[mb_x][0];
} else if (nb_components == 2) {
for (mb_x = 0; mb_x < 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];
}
}
} else {
for(i=0; i<nb_components; i++) {

7
libavcodec/tiff.c
View File

@ -839,6 +839,13 @@ static int dng_decode_jpeg_tile(AVCodecContext *avctx, AVFrame *frame,
jpkt.data = (uint8_t*)s->gb.buffer;
jpkt.size = tile_byte_count;
if (s->is_bayer) {
MJpegDecodeContext *mjpegdecctx = s->avctx_mjpeg->priv_data;
/* We have to set this information here, there is no way to know if a given JPEG is a DNG-embedded
image or not from its own data (and we need that information when decoding it). */
mjpegdecctx->bayer = 1;
}
ret = avcodec_send_packet(s->avctx_mjpeg, &jpkt);
if (ret < 0) {
av_log(avctx, AV_LOG_ERROR, "Error submitting a packet for decoding\n");