[FFmpeg-devel] [PATCH 2/2] avcodec/pngdec: read colorspace info when decoding with AVDISCARD_ALL
Leo Izen
leo.izen at gmail.com
Wed Feb 1 19:12:27 EET 2023
These chunks are lightweight and it's useful information to have when
running ffmpeg -i or ffprobe, for example.
Signed-off-by: Leo Izen <leo.izen at gmail.com>
---
libavcodec/pngdec.c | 126 ++++++++++++++++++++++++++------------------
1 file changed, 75 insertions(+), 51 deletions(-)
diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 0d969decf2..c83da08eb9 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -75,6 +75,7 @@ typedef struct PNGDecContext {
int have_chrm;
uint32_t white_point[2];
uint32_t display_primaries[3][2];
+ int gamma;
int have_srgb;
int have_cicp;
enum AVColorPrimaries cicp_primaries;
@@ -1203,7 +1204,7 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
if (avctx->codec_id == AV_CODEC_ID_PNG &&
avctx->skip_frame == AVDISCARD_ALL) {
- return 0;
+ goto exit_loop;
}
if (CONFIG_APNG_DECODER && avctx->codec_id == AV_CODEC_ID_APNG && length == 0) {
@@ -1256,6 +1257,10 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
case MKTAG('t', 'E', 'X', 't'):
case MKTAG('I', 'D', 'A', 'T'):
case MKTAG('t', 'R', 'N', 'S'):
+ case MKTAG('s', 'R', 'G', 'B'):
+ case MKTAG('c', 'I', 'C', 'P'):
+ case MKTAG('c', 'H', 'R', 'M'):
+ case MKTAG('g', 'A', 'M', 'A'):
break;
default:
continue;
@@ -1358,10 +1363,10 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
case MKTAG('g', 'A', 'M', 'A'): {
AVBPrint bp;
char *gamma_str;
- int num = bytestream2_get_be32(&gb_chunk);
+ s->gamma = bytestream2_get_be32(&gb_chunk);
av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
- av_bprintf(&bp, "%i/%i", num, 100000);
+ av_bprintf(&bp, "%i/%i", s->gamma, 100000);
ret = av_bprint_finalize(&bp, &gamma_str);
if (ret < 0)
return ret;
@@ -1382,6 +1387,73 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
}
exit_loop:
+ if (s->have_cicp) {
+ if (s->cicp_primaries >= AVCOL_PRI_NB)
+ av_log(avctx, AV_LOG_WARNING, "unrecognized cICP primaries\n");
+ else
+ avctx->color_primaries = p->color_primaries = s->cicp_primaries;
+ if (s->cicp_trc >= AVCOL_TRC_NB)
+ av_log(avctx, AV_LOG_WARNING, "unrecognized cICP transfer\n");
+ else
+ avctx->color_trc = p->color_trc = s->cicp_trc;
+ /* we don't support tv-range RGB */
+ avctx->color_range = p->color_range = AVCOL_RANGE_JPEG;
+ if (s->cicp_range == 0)
+ av_log(avctx, AV_LOG_WARNING, "unsupported tv-range cICP chunk\n");
+ } else if (s->iccp_data) {
+ AVFrameSideData *sd = av_frame_new_side_data(p, AV_FRAME_DATA_ICC_PROFILE, s->iccp_data_len);
+ if (!sd) {
+ ret = AVERROR(ENOMEM);
+ goto fail;
+ }
+ memcpy(sd->data, s->iccp_data, s->iccp_data_len);
+
+ av_dict_set(&sd->metadata, "name", s->iccp_name, 0);
+ } else if (s->have_srgb) {
+ avctx->color_primaries = p->color_primaries = AVCOL_PRI_BT709;
+ avctx->color_trc = p->color_trc = AVCOL_TRC_IEC61966_2_1;
+ } else if (s->have_chrm) {
+ AVColorPrimariesDesc desc;
+ enum AVColorPrimaries prim;
+ desc.wp.x = av_make_q(s->white_point[0], 100000);
+ desc.wp.y = av_make_q(s->white_point[1], 100000);
+ desc.prim.r.x = av_make_q(s->display_primaries[0][0], 100000);
+ desc.prim.r.y = av_make_q(s->display_primaries[0][1], 100000);
+ desc.prim.g.x = av_make_q(s->display_primaries[1][0], 100000);
+ desc.prim.g.y = av_make_q(s->display_primaries[1][1], 100000);
+ desc.prim.b.x = av_make_q(s->display_primaries[2][0], 100000);
+ desc.prim.b.y = av_make_q(s->display_primaries[2][1], 100000);
+ prim = av_csp_primaries_id_from_desc(&desc);
+ if (prim != AVCOL_PRI_UNSPECIFIED)
+ avctx->color_primaries = p->color_primaries = prim;
+ else
+ av_log(avctx, AV_LOG_WARNING, "unknown cHRM primaries\n");
+ }
+
+ /* these chunks override gAMA */
+ if (s->iccp_data || s->have_srgb || s->have_cicp) {
+ av_dict_set(&s->frame_metadata, "gamma", NULL, 0);
+ } else if (s->gamma) {
+ /*
+ * these values are 100000/2.2, 100000/2.8, and 100000/2.6
+ * respectively. 45455, 35714, and 38462. There's a 0.001
+ * gamma tolerance here in case of floating point issues
+ * when the PNG was written.
+ *
+ * None of the other enums have a pure gamma curve so it makes
+ * sense to leave those to sRGB and cICP.
+ */
+ if (s->gamma > 45355 && s->gamma < 45555)
+ avctx->color_trc = p->color_trc = AVCOL_TRC_GAMMA22;
+ else if (s->gamma > 35614 && s->gamma < 35814)
+ avctx->color_trc = p->color_trc = AVCOL_TRC_GAMMA28;
+ else if (s->gamma > 38362 && s->gamma < 38562)
+ avctx->color_trc = p->color_trc = AVCOL_TRC_SMPTE428;
+ }
+
+ avctx->colorspace = p->colorspace = AVCOL_SPC_RGB;
+ avctx->color_range = p->color_range = AVCOL_RANGE_JPEG;
+
if (avctx->codec_id == AV_CODEC_ID_PNG &&
avctx->skip_frame == AVDISCARD_ALL) {
return 0;
@@ -1499,56 +1571,8 @@ static void clear_frame_metadata(PNGDecContext *s)
static int output_frame(PNGDecContext *s, AVFrame *f)
{
- AVCodecContext *avctx = s->avctx;
int ret;
- if (s->have_cicp) {
- if (s->cicp_primaries >= AVCOL_PRI_NB)
- av_log(avctx, AV_LOG_WARNING, "unrecognized cICP primaries\n");
- else
- avctx->color_primaries = f->color_primaries = s->cicp_primaries;
- if (s->cicp_trc >= AVCOL_TRC_NB)
- av_log(avctx, AV_LOG_WARNING, "unrecognized cICP transfer\n");
- else
- avctx->color_trc = f->color_trc = s->cicp_trc;
- avctx->color_range = f->color_range =
- s->cicp_range == 0 ? AVCOL_RANGE_MPEG : AVCOL_RANGE_JPEG;
- } else if (s->iccp_data) {
- AVFrameSideData *sd = av_frame_new_side_data(f, AV_FRAME_DATA_ICC_PROFILE, s->iccp_data_len);
- if (!sd) {
- ret = AVERROR(ENOMEM);
- goto fail;
- }
- memcpy(sd->data, s->iccp_data, s->iccp_data_len);
-
- av_dict_set(&sd->metadata, "name", s->iccp_name, 0);
- } else if (s->have_srgb) {
- avctx->color_primaries = f->color_primaries = AVCOL_PRI_BT709;
- avctx->color_trc = f->color_trc = AVCOL_TRC_IEC61966_2_1;
- } else if (s->have_chrm) {
- AVColorPrimariesDesc desc;
- enum AVColorPrimaries prim;
- desc.wp.x = av_make_q(s->white_point[0], 100000);
- desc.wp.y = av_make_q(s->white_point[1], 100000);
- desc.prim.r.x = av_make_q(s->display_primaries[0][0], 100000);
- desc.prim.r.y = av_make_q(s->display_primaries[0][1], 100000);
- desc.prim.g.x = av_make_q(s->display_primaries[1][0], 100000);
- desc.prim.g.y = av_make_q(s->display_primaries[1][1], 100000);
- desc.prim.b.x = av_make_q(s->display_primaries[2][0], 100000);
- desc.prim.b.y = av_make_q(s->display_primaries[2][1], 100000);
- prim = av_csp_primaries_id_from_desc(&desc);
- if (prim != AVCOL_PRI_UNSPECIFIED)
- avctx->color_primaries = f->color_primaries = prim;
- else
- av_log(avctx, AV_LOG_WARNING, "unknown cHRM primaries\n");
- }
-
- /* these chunks override gAMA */
- if (s->iccp_data || s->have_srgb || s->have_cicp)
- av_dict_set(&s->frame_metadata, "gamma", NULL, 0);
-
- avctx->colorspace = f->colorspace = AVCOL_SPC_RGB;
-
if (s->stereo_mode >= 0) {
AVStereo3D *stereo3d = av_stereo3d_create_side_data(f);
if (!stereo3d) {
--
2.39.1
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