Make Y4mFrameGenerator read FPS from file format.

Bug: b/269577953
Change-Id: Ied0072e1fdfbfb4d2b11e74a814c0718cad01d66
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/294862
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39401}

api/test/frame_generator_interface.h

@@ -49,6 +49,12 @@ class FrameGeneratorInterface {
   virtual void ChangeResolution(size_t width, size_t height) = 0;
 
   virtual Resolution GetResolution() const = 0;
+
+  // Returns the frames per second this generator is supposed to provide
+  // according to its data source. Not all frame generators know the frames per
+  // second of the data source, in such case this method returns absl::nullopt.
+  // TODO(mbonadei): Make this pure virtual.
+  virtual absl::optional<int> fps() const { return absl::nullopt; }
 };
 
 }  // namespace test

test/BUILD.gn

@@ -92,7 +92,10 @@ rtc_library("y4m_frame_generator") {
     "../api/video:video_frame",
     "../rtc_base:checks",
   ]
-  absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
+  absl_deps = [
+    "//third_party/abseil-cpp/absl/strings",
+    "//third_party/abseil-cpp/absl/types:optional",
+  ]
 }
 
 rtc_library("frame_utils") {

test/frame_generator.h

@@ -40,6 +40,8 @@ class SquareGenerator : public FrameGeneratorInterface {
   VideoFrameData NextFrame() override;
   Resolution GetResolution() const override;
 
+  absl::optional<int> fps() const override { return absl::nullopt; }
+
  private:
   rtc::scoped_refptr<I420Buffer> CreateI420Buffer(int width, int height);
 
@@ -82,6 +84,8 @@ class YuvFileGenerator : public FrameGeneratorInterface {
   }
   Resolution GetResolution() const override;
 
+  absl::optional<int> fps() const override { return absl::nullopt; }
+
  private:
   // Returns true if the new frame was loaded.
   // False only in case of a single file with a single frame in it.
@@ -115,6 +119,8 @@ class NV12FileGenerator : public FrameGeneratorInterface {
   }
   Resolution GetResolution() const override;
 
+  absl::optional<int> fps() const override { return absl::nullopt; }
+
  private:
   // Returns true if the new frame was loaded.
   // False only in case of a single file with a single frame in it.
@@ -145,6 +151,8 @@ class SlideGenerator : public FrameGeneratorInterface {
   }
   Resolution GetResolution() const override;
 
+  absl::optional<int> fps() const override { return absl::nullopt; }
+
  private:
   // Generates some randomly sized and colored squares scattered
   // over the frame.
@@ -177,6 +185,8 @@ class ScrollingImageFrameGenerator : public FrameGeneratorInterface {
   }
   Resolution GetResolution() const override;
 
+  absl::optional<int> fps() const override { return absl::nullopt; }
+
  private:
   void UpdateSourceFrame(size_t frame_num);
   void CropSourceToScrolledImage(double scroll_factor);

test/testsupport/ivf_video_frame_generator.h

@@ -37,6 +37,8 @@ class IvfVideoFrameGenerator : public FrameGeneratorInterface {
   void ChangeResolution(size_t width, size_t height) override;
   Resolution GetResolution() const override;
 
+  absl::optional<int> fps() const override { return absl::nullopt; }
+
  private:
   class DecodedCallback : public DecodedImageCallback {
    public:

test/testsupport/ivf_video_frame_generator_unittest.cc

@@ -164,6 +164,12 @@ class IvfVideoFrameGeneratorTest : public ::testing::Test {
 
 }  // namespace
 
+TEST_F(IvfVideoFrameGeneratorTest, DoesNotKnowFps) {
+  CreateTestVideoFile(VideoCodecType::kVideoCodecVP8, VP8Encoder::Create());
+  IvfVideoFrameGenerator generator(file_name_);
+  EXPECT_EQ(generator.fps(), absl::nullopt);
+}
+
 TEST_F(IvfVideoFrameGeneratorTest, Vp8) {
   CreateTestVideoFile(VideoCodecType::kVideoCodecVP8, VP8Encoder::Create());
   IvfVideoFrameGenerator generator(file_name_);

test/testsupport/y4m_frame_generator.cc

@@ -41,7 +41,11 @@ Y4mFrameGenerator::Y4mFrameGenerator(absl::string_view filename,
   RTC_CHECK(fgets(header, sizeof(header), file) != nullptr)
       << "File " << filename_ << " is too small";
   fclose(file);
-  RTC_CHECK_EQ(sscanf(header, "YUV4MPEG2 W%zu H%zu", &width_, &height_), 2);
+  int fps_denominator;
+  RTC_CHECK_EQ(sscanf(header, "YUV4MPEG2 W%zu H%zu F%i:%i", &width_, &height_,
+                      &fps_, &fps_denominator),
+               4);
+  fps_ /= fps_denominator;
   RTC_CHECK_GT(width_, 0);
   RTC_CHECK_GT(height_, 0);
 

test/testsupport/y4m_frame_generator.h

@@ -16,6 +16,7 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
 #include "api/test/frame_generator_interface.h"
 #include "rtc_base/checks.h"
 #include "test/testsupport/frame_reader.h"
@@ -50,6 +51,8 @@ class Y4mFrameGenerator : public FrameGeneratorInterface {
 
   Resolution GetResolution() const override;
 
+  absl::optional<int> fps() const override { return fps_; }
+
  private:
   YuvFrameReaderImpl::RepeatMode ToYuvFrameReaderRepeatMode(
       RepeatMode repeat_mode) const;
@@ -57,6 +60,7 @@ class Y4mFrameGenerator : public FrameGeneratorInterface {
   std::string filename_;
   size_t width_;
   size_t height_;
+  int fps_;
   const RepeatMode repeat_mode_;
 };
 

test/testsupport/y4m_frame_generator_test.cc

@@ -56,6 +56,32 @@ TEST_F(Y4mFrameGeneratorTest, CanReadResolutionFromFile) {
   EXPECT_EQ(res.height, 2u);
 }
 
+TEST_F(Y4mFrameGeneratorTest, CanReadFPSFromFile) {
+  Y4mFrameGenerator generator(input_filepath_,
+                              Y4mFrameGenerator::RepeatMode::kSingle);
+  EXPECT_EQ(*generator.fps(), 2);
+}
+
+TEST_F(Y4mFrameGeneratorTest, CanReadFPSFromFileWhenRoundingIsNeeded) {
+  std::string input_filepath = TempFilename(OutputPath(), "2x2_23_FPS.y4m");
+  FILE* y4m_file = fopen(input_filepath.c_str(), "wb");
+
+  // Input Y4M file: 3 YUV frames of 2x2 resolution.
+  std::string y4m_content =
+      "YUV4MPEG2 W2 H2 F24000:1001 C420\n"
+      "FRAME\n"
+      "123456FRAME\n"
+      "abcdefFRAME\n"
+      "987654";
+  std::fprintf(y4m_file, "%s", y4m_content.c_str());
+  fclose(y4m_file);
+
+  Y4mFrameGenerator generator(input_filepath,
+                              Y4mFrameGenerator::RepeatMode::kSingle);
+  EXPECT_EQ(generator.fps(), 23);
+  remove(input_filepath.c_str());
+}
+
 TEST_F(Y4mFrameGeneratorTest, SingleRepeatMode) {
   Y4mFrameGenerator generator(input_filepath_,
                               Y4mFrameGenerator::RepeatMode::kSingle);