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From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH v3 2/3] avcodec/pngdec: read colorspace info when decoding with AVDISCARD_ALL
Date: Sun, 5 Feb 2023 04:47:00 +0100
Message-ID: <AS8P250MB0744B0DECB2CC7420CFC39C68FD59@AS8P250MB0744.EURP250.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20230202150938.22297-3-leo.izen@gmail.com>

Leo Izen:
> These chunks are lightweight and it's useful information to have when
> running ffmpeg -i or ffprobe, for example.
> ---
>  libavcodec/pngdec.c          | 103 ++++++++++++++++++-----------------
>  tests/ref/fate/png-icc       |   8 +--
>  tests/ref/fate/png-side-data |   2 +-
>  3 files changed, 59 insertions(+), 54 deletions(-)
> 
> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> index 0d969decf2..a80e0d15bb 100644
> --- a/libavcodec/pngdec.c
> +++ b/libavcodec/pngdec.c
> @@ -1203,7 +1203,7 @@ 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 +1256,9 @@ 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'):
>                  break;
>              default:
>                  continue;
> @@ -1382,6 +1385,56 @@ 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;

This code (both the new code as well as the old code in output_frame()
added in 6f79f0971e8 and f7bab37c8e6 and 2548c32cc10) modify avctx
fields after ff_thread_finish_setup() and are racy with respect to the
generic copying of AVCodecContext fields in update_context_from_thread()
in pthread_frame.c.

> +        /* we don't support tv-range RGB */
> +        avctx->color_range = p->color_range = AVCOL_RANGE_JPEG;

You set this unconditionally below, too.

> +        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);
> +
> +    avctx->colorspace = p->colorspace = AVCOL_SPC_RGB;
> +    avctx->color_range = p->color_range = AVCOL_RANGE_JPEG;

This is new in this patch; it changes behaviour even when nothing is
discarded. Is this intended?

> +
>      if (avctx->codec_id == AV_CODEC_ID_PNG &&
>          avctx->skip_frame == AVDISCARD_ALL) {
>          return 0;
> @@ -1499,56 +1552,8 @@ 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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  reply	other threads:[~2023-02-05  3:46 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-02 15:09 [FFmpeg-devel] [PATCH v3 0/3] PNG color tagging improvements Leo Izen
2023-02-02 15:09 ` [FFmpeg-devel] [PATCH v3 1/3] avcodec/pngenc: avoid writing cICP when inappropriate Leo Izen
2023-02-07 19:17   ` Leo Izen
2023-02-08 13:55     ` Leo Izen
2023-02-02 15:09 ` [FFmpeg-devel] [PATCH v3 2/3] avcodec/pngdec: read colorspace info when decoding with AVDISCARD_ALL Leo Izen
2023-02-05  3:47   ` Andreas Rheinhardt [this message]
2023-02-05  4:57     ` Leo Izen
2023-02-02 15:09 ` [FFmpeg-devel] [PATCH v3 3/3] avcodec/pngdec: populate enum transfer values from gAMA chunk Leo Izen

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