[FFmpeg-devel] [PATCH v2 2/2] avcodec/pngdec: read colorspace info when decoding with AVDISCARD_ALL
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Wed Feb 1 21:32:09 EET 2023
Leo Izen:
> 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 +++++++++++++++++++++--------------
> tests/ref/fate/png-icc | 8 +--
> tests/ref/fate/png-side-data | 2 +-
> 3 files changed, 80 insertions(+), 56 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;
It seems that this patch does more than the commit message claims.
> + }
> +
> + 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) {
> diff --git a/tests/ref/fate/png-icc b/tests/ref/fate/png-icc
> index 14de544639..1f4eab1fb0 100644
> --- a/tests/ref/fate/png-icc
> +++ b/tests/ref/fate/png-icc
> @@ -1,5 +1,5 @@
> -a50d37a0e72bddea2fcbba6fb773e2a0 *tests/data/fate/png-icc.image2
> -49397 tests/data/fate/png-icc.image2
> +c460cd06a88ace94d7c76a6309aa8fb8 *tests/data/fate/png-icc.image2
> +49441 tests/data/fate/png-icc.image2
> #tb 0: 1/25
> #media_type 0: video
> #codec_id 0: rawvideo
> @@ -21,7 +21,7 @@ pkt_duration_time=0.040000
> duration=1
> duration_time=0.040000
> pkt_pos=0
> -pkt_size=49397
> +pkt_size=49441
> width=128
> height=128
> pix_fmt=rgb24
> @@ -34,7 +34,7 @@ top_field_first=0
> repeat_pict=0
> color_range=pc
> color_space=gbr
> -color_primaries=unknown
> +color_primaries=bt709
> color_transfer=unknown
> chroma_location=unspecified
> [SIDE_DATA]
> diff --git a/tests/ref/fate/png-side-data b/tests/ref/fate/png-side-data
> index a4c16eb395..8f955f76bc 100644
> --- a/tests/ref/fate/png-side-data
> +++ b/tests/ref/fate/png-side-data
> @@ -26,7 +26,7 @@ top_field_first=0
> repeat_pict=0
> color_range=pc
> color_space=gbr
> -color_primaries=unknown
> +color_primaries=bt709
> color_transfer=unknown
> chroma_location=unspecified
> [SIDE_DATA]
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