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LibVideo: Treat BT.601/709/2020 input transfer characteristics as sRGB

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I've realized that it probably makes more sense to change the input
transfer characteristics to treat these as sRGB since color conversion
in linear converted from BT.709 doesn't really make sense. If content
creation applications expect media players to display BT.709 without
conversions, this means they expect applications to treat it as sRGB,
since that's what most displays use. That most likely also means they
process it as sRGB internally, meaning we should do the same for our
color primaries conversion.
This commit is contained in:
Zaggy1024 2022-11-08 03:24:30 -06:00 • committed by Andreas Kling
parent a2cd61d19d
commit 6b392cef9c
2 changed files with 16 additions and 16 deletions
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15
Userland/Libraries/LibVideo/Color/ColorConverter.cpp
View file

@ -165,21 +165,6 @@ DecoderErrorOr<ColorConverter> ColorConverter::create(u8 bit_depth, CodingIndepe
// should apply tonemapping as well.
// Use a lookup table as with step 3.
TransferCharacteristics output_tc = TransferCharacteristics::SRGB;
switch (cicp.transfer_characteristics()) {
case TransferCharacteristics::Unspecified:
break;
case TransferCharacteristics::BT709:
case TransferCharacteristics::BT601:
case TransferCharacteristics::BT2020BitDepth10:
case TransferCharacteristics::BT2020BitDepth12:
// BT.601, BT.709 and BT.2020 have a similar transfer function to sRGB, and other applications
// (Chromium, VLC) seem to keep video output in those transfer characteristics.
output_tc = TransferCharacteristics::BT709;
break;
default:
break;
}
auto to_non_linear_lookup_table = InterpolatedLookupTable<to_non_linear_size>::create(
[&](float value) {
return TransferCharacteristicsConversion::to_non_linear_luminance(value, output_tc);

17
Userland/Libraries/LibVideo/PlaybackManager.cpp
View file

@ -221,7 +221,22 @@ bool PlaybackManager::decode_and_queue_one_sample()
auto& cicp = decoded_frame->cicp();
cicp.adopt_specified_values(frame_sample->container_cicp());
cicp.default_code_points_if_unspecified({ Video::ColorPrimaries::BT709, Video::TransferCharacteristics::BT709, Video::MatrixCoefficients::BT709, Video::ColorRange::Studio });
cicp.default_code_points_if_unspecified({ ColorPrimaries::BT709, TransferCharacteristics::BT709, MatrixCoefficients::BT709, ColorRange::Studio });
// BT.601, BT.709 and BT.2020 have a similar transfer function to sRGB, so other applications
// (Chromium, VLC) forgo transfer characteristics conversion. We will emulate that behavior by
// handling those as sRGB instead, which causes no transfer function change in the output,
// unless display color management is later implemented.
switch (cicp.transfer_characteristics()) {
case TransferCharacteristics::BT601:
case TransferCharacteristics::BT709:
case TransferCharacteristics::BT2020BitDepth10:
case TransferCharacteristics::BT2020BitDepth12:
cicp.set_transfer_characteristics(TransferCharacteristics::SRGB);
break;
default:
break;
}
auto bitmap = TRY_OR_ENQUEUE_ERROR(decoded_frame->to_bitmap());
m_frame_queue->enqueue(FrameQueueItem::frame(bitmap, frame_sample->timestamp()));