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[GST] Expose VIDEO_DECODING_LIMIT through env variable #1626

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[GST] Expose VIDEO_DECODING_LIMIT through env variable #1626

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61498ea
[GStreamer] refactor video decoder limit customization
pgorszkowski-igalia Apr 26, 2023
060f917
[GStreamer] Avoid using decoding limits for all configurations
blino Nov 17, 2023
30a2934
[GStreamer] Fix content type frame rate limit
filipe-norte-red Jul 29, 2025
83cf389
Expose VIDEO_DECODING_LIMIT through env variable
asurdej-comcast Feb 26, 2026
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2 changes: 1 addition & 1 deletion Source/WebCore/platform/GStreamer.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -170,7 +170,7 @@ if (ENABLE_VIDEO OR ENABLE_WEB_AUDIO)

if (VIDEO_DECODING_LIMIT)
# Specify video decoding limits.
set_source_files_properties(platform/graphics/gstreamer/mse/MediaPlayerPrivateGStreamerMSE.cpp PROPERTIES COMPILE_DEFINITIONS VIDEO_DECODING_LIMIT="${VIDEO_DECODING_LIMIT}")
set_source_files_properties(platform/graphics/gstreamer/GStreamerRegistryScanner.cpp PROPERTIES COMPILE_DEFINITIONS VIDEO_DECODING_LIMIT="${VIDEO_DECODING_LIMIT}")
endif ()
endif ()

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116 changes: 107 additions & 9 deletions Source/WebCore/platform/graphics/gstreamer/GStreamerRegistryScanner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,92 @@
#include "VideoEncoderPrivateGStreamer.h"
#endif

namespace {
struct VideoDecodingLimits {
unsigned mediaMaxWidth = 0;
unsigned mediaMaxHeight = 0;
unsigned mediaMaxFrameRate = 0;
VideoDecodingLimits(unsigned mediaMaxWidth, unsigned mediaMaxHeight, unsigned mediaMaxFrameRate)
: mediaMaxWidth(mediaMaxWidth)
, mediaMaxHeight(mediaMaxHeight)
, mediaMaxFrameRate(mediaMaxFrameRate)
{
}
};

// Parses a video decoding limit string in format WIDTHxHEIGHT@FRAMERATE.
static std::optional<VideoDecodingLimits> parseVideoDecodingLimit(const String& videoDecodingLimit)
{
if (videoDecodingLimit.isEmpty())
return { };

Vector<String> entries;

// Extract frame rate part: WIDTHxHEIGHT@FRAMERATE.
videoDecodingLimit.split('@', [&entries](StringView item) {
entries.append(item.toString());
});

if (entries.size() != 2)
return { };

auto frameRate = parseIntegerAllowingTrailingJunk<unsigned>(entries[1]);

if (!frameRate.has_value())
return { };

const auto widthAndHeight = entries[0].split('x');

if (widthAndHeight.size() != 2)
return { };

const auto width = parseIntegerAllowingTrailingJunk<unsigned>(widthAndHeight[0]);

if (!width.has_value())
return { };

const auto height = parseIntegerAllowingTrailingJunk<unsigned>(widthAndHeight[1]);

if (!height.has_value())
return { };

return { VideoDecodingLimits(width.value(), height.value(), frameRate.value()) };
}

// Returns the active VideoDecodingLimits, resolved once at first call.
// WEBKIT_GST_VIDEO_DECODING_LIMIT env var takes precedence over the compile-time VIDEO_DECODING_LIMIT.
// Format for both: WIDTHxHEIGHT@FRAMERATE (e.g. "1920x1080@30").
static VideoDecodingLimits* resolveVideoDecodingLimits()
{
static std::optional<VideoDecodingLimits> limits;
static std::once_flag onceFlag;
std::call_once(onceFlag, [] {
if (const char* envLimit = g_getenv("WEBKIT_GST_VIDEO_DECODING_LIMIT")) {
GST_DEBUG("WEBKIT_GST_VIDEO_DECODING_LIMIT env var is set: %s", envLimit);
limits = parseVideoDecodingLimit(String::fromUTF8(envLimit));
if (!limits)
GST_WARNING("Parsing WEBKIT_GST_VIDEO_DECODING_LIMIT env var failed: %s", envLimit);
}
#ifdef VIDEO_DECODING_LIMIT
if (!limits) {
GST_DEBUG("VIDEO_DECODING_LIMIT compile-time definition is set: %s", VIDEO_DECODING_LIMIT);
limits = parseVideoDecodingLimit(String::fromUTF8(VIDEO_DECODING_LIMIT));
if (!limits) {
GST_WARNING("Parsing VIDEO_DECODING_LIMIT failed: %s", VIDEO_DECODING_LIMIT);
ASSERT_NOT_REACHED();
}
}
#endif
if (limits) {
GST_DEBUG("Video decoding limits: max width=%u, max height=%u, max frame rate=%u",
limits->mediaMaxWidth, limits->mediaMaxHeight, limits->mediaMaxFrameRate);
}
});
return limits ? &*limits : nullptr;
}

} // namespace

namespace WebCore {

GST_DEBUG_CATEGORY_STATIC(webkit_media_gst_registry_scanner_debug);
Expand All @@ -50,11 +136,6 @@ GST_DEBUG_CATEGORY_STATIC(webkit_media_gst_registry_scanner_debug);
// AAC supports up to 96 channels.
#define MEDIA_MAX_AAC_CHANNELS 96

// Assume hardware video decoding acceleration up to 8K@60fps for the generic case. Some embedded platforms might want to tune this.
#define MEDIA_MAX_WIDTH 7680.0f
#define MEDIA_MAX_HEIGHT 4320.0f
#define MEDIA_MAX_FRAMERATE 60.0f

static bool singletonInitialized = false;

bool GStreamerRegistryScanner::singletonWasInitialized()
Expand Down Expand Up @@ -705,6 +786,10 @@ bool GStreamerRegistryScanner::supportsFeatures(const String& features) const

MediaPlayerEnums::SupportsType GStreamerRegistryScanner::isContentTypeSupported(Configuration configuration, const ContentType& contentType, const Vector<ContentType>& contentTypesRequiringHardwareSupport) const
{
VideoDecodingLimits* videoDecodingLimits = nullptr;
if (configuration == Configuration::Decoding)
videoDecodingLimits = resolveVideoDecodingLimits();

using SupportsType = MediaPlayerEnums::SupportsType;

const auto& containerType = contentType.containerType().convertToASCIILowercase();
Expand All @@ -714,10 +799,23 @@ MediaPlayerEnums::SupportsType GStreamerRegistryScanner::isContentTypeSupported(
int channels = parseInteger<int>(contentType.parameter("channels"_s)).value_or(1);
String features = contentType.parameter("features"_s);
if (channels > MEDIA_MAX_AAC_CHANNELS || channels <= 0
|| !(features.isEmpty() || supportsFeatures(features))
|| parseInteger<unsigned>(contentType.parameter("width"_s)).value_or(0) > MEDIA_MAX_WIDTH
|| parseInteger<unsigned>(contentType.parameter("height"_s)).value_or(0) > MEDIA_MAX_HEIGHT
|| parseInteger<unsigned>(contentType.parameter("framerate"_s)).value_or(0) > MEDIA_MAX_FRAMERATE)
|| !(features.isEmpty() || supportsFeatures(features)))
return SupportsType::IsNotSupported;

bool ok;
float width = contentType.parameter("width"_s).toFloat(&ok);
if (!ok)
width = 0;
float height = contentType.parameter("height"_s).toFloat(&ok);
if (!ok)
height = 0;

float frameRate = contentType.parameter("framerate"_s).toFloat(&ok);
if (!ok)
frameRate = 0;

if (videoDecodingLimits && (width > videoDecodingLimits->mediaMaxWidth || height > videoDecodingLimits->mediaMaxHeight
|| frameRate > videoDecodingLimits->mediaMaxFrameRate))
return SupportsType::IsNotSupported;

const auto& codecs = contentType.codecs();
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97 changes: 0 additions & 97 deletions Source/WebCore/platform/graphics/gstreamer/mse/MediaPlayerPrivateGStreamerMSE.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -56,73 +56,6 @@
#include <wtf/text/AtomStringHash.h>
#include <wtf/text/StringToIntegerConversion.h>

namespace {
struct VideoDecodingLimits {
unsigned mediaMaxWidth = 0;
unsigned mediaMaxHeight = 0;
unsigned mediaMaxFrameRate = 0;
VideoDecodingLimits(unsigned mediaMaxWidth, unsigned mediaMaxHeight, unsigned mediaMaxFrameRate)
: mediaMaxWidth(mediaMaxWidth)
, mediaMaxHeight(mediaMaxHeight)
, mediaMaxFrameRate(mediaMaxFrameRate)
{
}
};
}

#ifdef VIDEO_DECODING_LIMIT
static std::optional<VideoDecodingLimits> videoDecoderLimitsDefaults()
{
// VIDEO_DECODING_LIMIT should be in format: WIDTHxHEIGHT@FRAMERATE.
String videoDecodingLimit(String::fromUTF8(VIDEO_DECODING_LIMIT));

if (videoDecodingLimit.isEmpty())
return { };

Vector<String> entries;

// Extract frame rate part from the VIDEO_DECODING_LIMIT: WIDTHxHEIGHT@FRAMERATE.
videoDecodingLimit.split('@', [&entries](StringView item) {
entries.append(item.toString());
});

if (entries.size() != 2)
return { };

auto frameRate = parseIntegerAllowingTrailingJunk<unsigned>(entries[1]);

if (!frameRate.has_value())
return { };

String widthAndHeight = entries[0];
entries.clear();

// Extract WIDTH and HEIGHT from: WIDTHxHEIGHT.
widthAndHeight.split('x', [&entries](StringView item) {
entries.append(item.toString());
});

if (entries.size() != 2)
return { };

auto width = parseIntegerAllowingTrailingJunk<unsigned>(entries[0]);

if (!width.has_value())
return { };

auto height = parseIntegerAllowingTrailingJunk<unsigned>(entries[1]);

if (!height.has_value())
return { };

return { VideoDecodingLimits(width.value(), height.value(), frameRate.value()) };
}
#endif

// We shouldn't accept media that the player can't actually play.
// AAC supports up to 96 channels.
#define MEDIA_MAX_AAC_CHANNELS 96

static const char* dumpReadyState(WebCore::MediaPlayer::ReadyState readyState)
{
switch (readyState) {
Expand Down Expand Up @@ -521,36 +454,6 @@ MediaPlayer::SupportsType MediaPlayerPrivateGStreamerMSE::supportsType(const Med
return result;
}

unsigned channels = parseIntegerAllowingTrailingJunk<unsigned>(parameters.type.parameter("channels"_s)).value_or(0);
if (channels > MEDIA_MAX_AAC_CHANNELS)
return result;

bool ok;
float width = parameters.type.parameter("width"_s).toFloat(&ok);
if (!ok)
width = 0;
float height = parameters.type.parameter("height"_s).toFloat(&ok);
if (!ok)
height = 0;

static std::optional<VideoDecodingLimits> videoDecodingLimits;
#ifdef VIDEO_DECODING_LIMIT
static std::once_flag onceFlag;
std::call_once(onceFlag, [] {
videoDecodingLimits = videoDecoderLimitsDefaults();
if (!videoDecodingLimits)
GST_WARNING("Parsing VIDEO_DECODING_LIMIT failed");
});
#endif

if (videoDecodingLimits && (width > videoDecodingLimits->mediaMaxWidth || height > videoDecodingLimits->mediaMaxHeight))
return result;

float frameRate = parameters.type.parameter("framerate"_s).toFloat(&ok);
// Limit frameRate only in case of highest supported resolution.
if (ok && videoDecodingLimits && width == videoDecodingLimits->mediaMaxWidth && height == videoDecodingLimits->mediaMaxHeight && frameRate > videoDecodingLimits->mediaMaxFrameRate)
return result;

registerWebKitGStreamerElements();

GST_DEBUG("Checking mime-type \"%s\"", parameters.type.raw().utf8().data());
Expand Down