From c29e1f54158539a8fd733c21cb9cf7885cbda24c Mon Sep 17 00:00:00 2001
From: Johannes Kron <kron@webrtc.org>
Date: Mon, 26 Apr 2021 22:18:57 +0200
Subject: [PATCH] Add QueryCodecSupport() to VideoEncoderFactory and
 VideoDecoderFactory
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QueryCodecSupport() is needed in the coming work with extending
the MediaCapabilities API to WebRTC. In the API, a user can query
whether a specified media configuration is supported, power
efficient, and smooth. QueryCodecSupport() will be used to determine
if the configuration is supported and power efficient.

Bug: chromium:1187565
Change-Id: Ib1d93433a180b433f0bf60d6e871d03cebc4c0a6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215922
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33843}
---
 api/video_codecs/video_decoder_factory.h | 28 +++++++++++++++++++++++-
 api/video_codecs/video_encoder_factory.h | 26 ++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/api/video_codecs/video_decoder_factory.h b/api/video_codecs/video_decoder_factory.h
index e4d83c2465..40a2c82faf 100644
--- a/api/video_codecs/video_decoder_factory.h
+++ b/api/video_codecs/video_decoder_factory.h
@@ -15,21 +15,47 @@
 #include <string>
 #include <vector>
 
+#include "absl/types/optional.h"
+#include "api/video_codecs/sdp_video_format.h"
 #include "rtc_base/system/rtc_export.h"
 
 namespace webrtc {
 
 class VideoDecoder;
-struct SdpVideoFormat;
 
 // A factory that creates VideoDecoders.
 // NOTE: This class is still under development and may change without notice.
 class RTC_EXPORT VideoDecoderFactory {
  public:
+  struct CodecSupport {
+    bool is_supported = false;
+    bool is_power_efficient = false;
+  };
+
   // Returns a list of supported video formats in order of preference, to use
   // for signaling etc.
   virtual std::vector<SdpVideoFormat> GetSupportedFormats() const = 0;
 
+  // Query whether the specifed format is supported or not and if it will be
+  // power efficient, which is currently interpreted as if there is support for
+  // hardware acceleration.
+  // See https://w3c.github.io/webrtc-svc/#scalabilitymodes* for a specification
+  // of valid values for |scalability_mode|.
+  // NOTE: QueryCodecSupport is currently an experimental feature that is
+  // subject to change without notice.
+  virtual CodecSupport QueryCodecSupport(
+      const SdpVideoFormat& format,
+      absl::optional<std::string> scalability_mode) const {
+    // Default implementation, query for supported formats and check if the
+    // specified format is supported. Returns false if scalability_mode is
+    // specified.
+    CodecSupport codec_support;
+    if (!scalability_mode) {
+      codec_support.is_supported = format.IsCodecInList(GetSupportedFormats());
+    }
+    return codec_support;
+  }
+
   // Creates a VideoDecoder for the specified format.
   virtual std::unique_ptr<VideoDecoder> CreateVideoDecoder(
       const SdpVideoFormat& format) = 0;
diff --git a/api/video_codecs/video_encoder_factory.h b/api/video_codecs/video_encoder_factory.h
index 22430eb19d..c2d66cfa86 100644
--- a/api/video_codecs/video_encoder_factory.h
+++ b/api/video_codecs/video_encoder_factory.h
@@ -12,6 +12,7 @@
 #define API_VIDEO_CODECS_VIDEO_ENCODER_FACTORY_H_
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "absl/types/optional.h"
@@ -36,6 +37,11 @@ class VideoEncoderFactory {
     bool has_internal_source = false;
   };
 
+  struct CodecSupport {
+    bool is_supported = false;
+    bool is_power_efficient = false;
+  };
+
   // An injectable class that is continuously updated with encoding conditions
   // and selects the best encoder given those conditions.
   class EncoderSelectorInterface {
@@ -78,6 +84,26 @@ class VideoEncoderFactory {
     return CodecInfo();
   }
 
+  // Query whether the specifed format is supported or not and if it will be
+  // power efficient, which is currently interpreted as if there is support for
+  // hardware acceleration.
+  // See https://w3c.github.io/webrtc-svc/#scalabilitymodes* for a specification
+  // of valid values for |scalability_mode|.
+  // NOTE: QueryCodecSupport is currently an experimental feature that is
+  // subject to change without notice.
+  virtual CodecSupport QueryCodecSupport(
+      const SdpVideoFormat& format,
+      absl::optional<std::string> scalability_mode) const {
+    // Default implementation, query for supported formats and check if the
+    // specified format is supported. Returns false if scalability_mode is
+    // specified.
+    CodecSupport codec_support;
+    if (!scalability_mode) {
+      codec_support.is_supported = format.IsCodecInList(GetSupportedFormats());
+    }
+    return codec_support;
+  }
+
   // Creates a VideoEncoder for the specified format.
   virtual std::unique_ptr<VideoEncoder> CreateVideoEncoder(
       const SdpVideoFormat& format) = 0;