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avcodec/tiff: Option to decode embedded thumbnail

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Adds the "-thumbnail" option, that works like the current "-subifd"
option, but only for non-full-sized images.

This is particularly useful for DNG images (see next commit) that
have SubIFDs that are not necessarily thumbnails.

Signed-off-by: Nick Renieris <velocityra@gmail.com>
This commit is contained in:
Nick Renieris 2019-05-30 13:42:40 +03:00 committed by Paul B Mahol
parent 6895b350c3
commit a7e018b05e
1 changed files with 14 additions and 3 deletions
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17
libavcodec/tiff.c
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@ -56,6 +56,7 @@ typedef struct TiffContext {
int get_subimage;
uint16_t get_page;
int get_thumbnail;
int width, height;
unsigned int bpp, bppcount;
@ -70,6 +71,7 @@ typedef struct TiffContext {
int predictor;
int fill_order;
uint32_t res[4];
int is_thumbnail;
int is_bayer;
uint8_t pattern[4];
@ -948,6 +950,8 @@ static int tiff_decode_tag(TiffContext *s, AVFrame *frame)
}
switch (tag) {
case TIFF_SUBFILE:
s->is_thumbnail = (value != 0);
case TIFF_WIDTH:
s->width = value;
break;
@ -1387,6 +1391,7 @@ static int decode_frame(AVCodecContext *avctx,
s->le = le;
// TIFF_BPP is not a required tag and defaults to 1
again:
s->is_thumbnail = 0;
s->bppcount = s->bpp = 1;
s->photometric = TIFF_PHOTOMETRIC_NONE;
s->compr = TIFF_RAW;
@ -1408,9 +1413,14 @@ again:
return ret;
}
/** whether we should look for this IFD's SubIFD */
retry_for_subifd = s->sub_ifd && s->get_subimage;
/** whether we should look for this multi-page IFD's next page */
if (s->get_thumbnail && !s->is_thumbnail) {
av_log(avctx, AV_LOG_INFO, "No embedded thumbnail present\n");
return AVERROR_EOF;
}
/** whether we should process this IFD's SubIFD */
retry_for_subifd = s->sub_ifd && (s->get_subimage || (!s->get_thumbnail && s->is_thumbnail));
/** whether we should process this multi-page IFD's next page */
retry_for_page = s->get_page && s->cur_page + 1 < s->get_page; // get_page is 1-indexed
if (retry_for_page) {
@ -1670,6 +1680,7 @@ static av_cold int tiff_end(AVCodecContext *avctx)
#define OFFSET(x) offsetof(TiffContext, x)
static const AVOption tiff_options[] = {
{ "subimage", "decode subimage instead if available", OFFSET(get_subimage), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM },
{ "thumbnail", "decode embedded thumbnail subimage instead if available", OFFSET(get_thumbnail), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM },
{ "page", "page number of multi-page image to decode (starting from 1)", OFFSET(get_page), AV_OPT_TYPE_INT, {.i64=0}, 0, UINT16_MAX, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM },
{ NULL },
};