[webcodecs] Make encoder's framerate optional

Bug: 1139059
Change-Id: I1e142da5f9f1d6c7cfce42294b9022a0fab1e12f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2520080Reviewed-by: Dan Sanders <sandersd@chromium.org>
Commit-Queue: Eugene Zemtsov <eugene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824706}

media/base/video_encoder.h

@@ -39,7 +39,7 @@ class MEDIA_EXPORT VideoEncoder {
     Options(const Options&);
     ~Options();
     base::Optional<uint64_t> bitrate;
-    double framerate = 30.0;
+    base::Optional<double> framerate;
 
     int width = 0;
     int height = 0;

media/video/openh264_video_encoder.cc

@@ -27,7 +27,8 @@ Status SetUpOpenH264Params(const VideoEncoder::Options& options,
   params->bEnableDenoise = false;
   // Set to 1 due to https://crbug.com/583348
   params->iMultipleThreadIdc = 1;
-  params->fMaxFrameRate = options.framerate;
+  if (options.framerate.has_value())
+    params->fMaxFrameRate = options.framerate.value();
   params->iPicHeight = options.height;
   params->iPicWidth = options.width;
 

media/video/vpx_video_encoder.cc

@@ -4,6 +4,7 @@
 
 #include "media/video/vpx_video_encoder.h"
 
+#include "base/numerics/ranges.h"
 #include "base/strings/stringprintf.h"
 #include "base/system/sys_info.h"
 #include "base/time/time.h"
@@ -275,12 +276,13 @@ void VpxVideoEncoder::Encode(scoped_refptr<VideoFrame> frame,
       break;
   }
 
-  auto timestamp = frame->timestamp().InMicroseconds();
-  auto duration = GetFrameDuration(*frame);
+  auto duration_us = GetFrameDuration(*frame).InMicroseconds();
+  auto timestamp_us = frame->timestamp().InMicroseconds();
+  last_frame_timestamp_ = frame->timestamp();
   auto deadline = VPX_DL_REALTIME;
   vpx_codec_flags_t flags = key_frame ? VPX_EFLAG_FORCE_KF : 0;
-  auto vpx_error = vpx_codec_encode(codec_.get(), &vpx_image_, timestamp,
-                                    duration, flags, deadline);
+  auto vpx_error = vpx_codec_encode(codec_.get(), &vpx_image_, timestamp_us,
+                                    duration_us, flags, deadline);
 
   if (vpx_error != VPX_CODEC_OK) {
     std::string msg = base::StringPrintf("VPX encoding error: %s (%s)",
@@ -321,12 +323,21 @@ void VpxVideoEncoder::ChangeOptions(const Options& options, StatusCB done_cb) {
   return;
 }
 
-uint64_t VpxVideoEncoder::GetFrameDuration(const VideoFrame& frame) {
-  base::TimeDelta default_duration =
-      base::TimeDelta::FromSecondsD(1.0 / options_.framerate);
-  return frame.metadata()
-      ->frame_duration.value_or(default_duration)
-      .InMicroseconds();
+base::TimeDelta VpxVideoEncoder::GetFrameDuration(const VideoFrame& frame) {
+  // Frame has duration in metadata, use it.
+  if (frame.metadata()->frame_duration.has_value())
+    return frame.metadata()->frame_duration.value();
+
+  // Options have framerate specified, use it.
+  if (options_.framerate.has_value())
+    return base::TimeDelta::FromSecondsD(1.0 / options_.framerate.value());
+
+  // No real way to figure out duration, use time passed since the last frame
+  // as an educated guess, but clamp it within a reasonable limits.
+  constexpr auto min_duration = base::TimeDelta::FromSecondsD(1.0 / 60.0);
+  constexpr auto max_duration = base::TimeDelta::FromSecondsD(1.0 / 24.0);
+  auto duration = frame.timestamp() - last_frame_timestamp_;
+  return base::ClampToRange(duration, min_duration, max_duration);
 }
 
 VpxVideoEncoder::~VpxVideoEncoder() {

media/video/vpx_video_encoder.h

@@ -32,7 +32,7 @@ class MEDIA_EXPORT VpxVideoEncoder : public VideoEncoder {
   void Flush(StatusCB done_cb) override;
 
  private:
-  uint64_t GetFrameDuration(const VideoFrame& frame);
+  base::TimeDelta GetFrameDuration(const VideoFrame& frame);
   void DrainOutputs();
 
   using vpx_codec_unique_ptr =
@@ -42,6 +42,7 @@ class MEDIA_EXPORT VpxVideoEncoder : public VideoEncoder {
   bool is_vp9_ = false;
   vpx_codec_enc_cfg_t codec_config_ = {};
   vpx_image_t vpx_image_ = {};
+  base::TimeDelta last_frame_timestamp_;
   VideoCodecProfile profile_ = VIDEO_CODEC_PROFILE_UNKNOWN;
   Options options_;
   OutputCB output_cb_;

third_party/blink/renderer/modules/webcodecs/video_encoder.cc

@@ -83,7 +83,8 @@ std::unique_ptr<media::VideoEncoder> CreateAcceleratedVideoEncoder(
     double max_supported_framerate =
         double{supported_profile.max_framerate_numerator} /
         supported_profile.max_framerate_denominator;
-    if (options.framerate > max_supported_framerate)
+    if (options.framerate.has_value() &&
+        options.framerate.value() > max_supported_framerate)
       continue;
 
     found_supported_profile = true;
@@ -198,7 +199,8 @@ std::unique_ptr<VideoEncoder::ParsedConfig> VideoEncoder::ParseConfig(
     return nullptr;
   }
 
-  parsed->options.framerate = config->framerate();
+  if (config->hasFramerate())
+    parsed->options.framerate = config->framerate();
 
   if (config->hasBitrate())
     parsed->options.bitrate = config->bitrate();

third_party/blink/renderer/modules/webcodecs/video_encoder_config.idl

@@ -17,7 +17,7 @@ dictionary VideoEncoderConfig {
 
   unsigned long long bitrate;
 
-  required double framerate;
+  double framerate;
 
   required unsigned long width;
   required unsigned long height;

third_party/blink/web_tests/webcodecs/basic_video_encoding.html

@@ -88,7 +88,6 @@
         width: w,
         height: h,
         bitrate: 5000000,
-        framerate: 30,
       };
 
       let encoder = new VideoEncoder(encoder_init);
@@ -135,7 +134,7 @@
       const init = {
         output: process_video_chunk,
         error: (e) => {
-          error++;
+          errors++;
           console.log(e.message);
         },
       };
@@ -180,11 +179,11 @@
       "encoding and decoding avc1.42001E");
 
     /* Uncomment this for manual testing, before we have GPU tests for that */
-    // promise_test(encode_test.bind(null, "avc1.42001E", "require"),
+    //promise_test(encode_test.bind(null, "avc1.42001E", "require"),
     //  "encoding avc1.42001E");
 
-    // promise_test(encode_decode_test.bind(null, "avc1.42001E", "require"),
-    //  "encoding and decoding avc1.42001E");
+    //promise_test(encode_decode_test.bind(null, "avc1.42001E", "require"),
+    //  "encoding and decoding avc1.42001E req");
 
 
   </script>