Decouple image conversion and OutputStream class (#3113)

Summary:
Pull Request resolved: https://github.com/pytorch/audio/pull/3113

Decouple the Tensor to AVFrame conversion process from encoding process.

Reviewed By: nateanl

Differential Revision: D43628942

fbshipit-source-id: e698f3150292567dbc23e7d6795ad58265f24780

torchaudio/csrc/ffmpeg/stream_writer/video_output_stream.cpp

@@ -117,59 +117,46 @@ void validate_video_input(
       t.sizes());
 }
 
-#ifdef USE_CUDA
 void write_interlaced_video_cuda(
-    VideoOutputStream& os,
-    const torch::Tensor& frames,
+    const torch::Tensor& chunk,
+    AVFrame* buffer,
     bool pad_extra) {
-  const auto num_frames = frames.size(0);
-  const auto num_channels = frames.size(1);
-  const auto height = frames.size(2);
-  const auto width = frames.size(3);
-  const auto num_channels_buffer = num_channels + (pad_extra ? 1 : 0);
-
-  using namespace torch::indexing;
-  torch::Tensor buffer =
-      torch::empty({height, width, num_channels_buffer}, frames.options());
-  size_t spitch = width * num_channels_buffer;
-  for (int i = 0; i < num_frames; ++i) {
-    // Slice frame as HWC
-    auto chunk = frames.index({i}).permute({1, 2, 0});
-    buffer.index_put_({"...", Slice(0, num_channels)}, chunk);
-
+#ifdef USE_CUDA
+  const auto height = chunk.size(0);
+  const auto width = chunk.size(1);
+  const auto num_channels = chunk.size(2) + (pad_extra ? 1 : 0);
+  size_t spitch = width * num_channels;
   if (cudaSuccess !=
       cudaMemcpy2D(
-            (void*)(os.src_frame->data[0]),
-            os.src_frame->linesize[0],
-            (const void*)(buffer.data_ptr<uint8_t>()),
+          (void*)(buffer->data[0]),
+          buffer->linesize[0],
+          (const void*)(chunk.data_ptr<uint8_t>()),
           spitch,
           spitch,
           height,
           cudaMemcpyDeviceToDevice)) {
     TORCH_CHECK(false, "Failed to copy pixel data from CUDA tensor.");
   }
-    os.process_frame();
-  }
+#else
+  TORCH_CHECK(
+      false,
+      "torchaudio is not compiled with CUDA support. Hardware acceleration is not available.");
+#endif
 }
 
 void write_planar_video_cuda(
-    VideoOutputStream& os,
-    const torch::Tensor& frames,
+    const torch::Tensor& chunk,
+    AVFrame* buffer,
     int num_planes) {
-  const auto num_frames = frames.size(0);
-  const auto height = frames.size(2);
-  const auto width = frames.size(3);
-
-  using namespace torch::indexing;
-  torch::Tensor buffer = torch::empty({height, width}, frames.options());
-  for (int i = 0; i < num_frames; ++i) {
+#ifdef USE_CUDA
+  const auto height = chunk.size(1);
+  const auto width = chunk.size(2);
   for (int j = 0; j < num_planes; ++j) {
-      buffer.index_put_({"..."}, frames.index({i, j}));
     if (cudaSuccess !=
         cudaMemcpy2D(
-              (void*)(os.src_frame->data[j]),
-              os.src_frame->linesize[j],
-              (const void*)(buffer.data_ptr<uint8_t>()),
+            (void*)(buffer->data[j]),
+            buffer->linesize[j],
+            (const void*)(chunk.index({j}).data_ptr<uint8_t>()),
             width,
             width,
             height,
@@ -177,10 +164,12 @@ void write_planar_video_cuda(
       TORCH_CHECK(false, "Failed to copy pixel data from CUDA tensor.");
     }
   }
-    os.process_frame();
-  }
-}
+#else
+  TORCH_CHECK(
+      false,
+      "torchaudio is not compiled with CUDA support. Hardware acceleration is not available.");
 #endif
+}
 
 // Interlaced video
 // Each frame is composed of one plane, and color components for each pixel are
@@ -193,35 +182,22 @@ void write_planar_video_cuda(
 // 1: RGB RGB ... RGB PAD ... PAD
 //            ...
 // H: RGB RGB ... RGB PAD ... PAD
-void write_interlaced_video(
-    VideoOutputStream& os,
-    const torch::Tensor& frames) {
-  const auto num_frames = frames.size(0);
-  const auto num_channels = frames.size(1);
-  const auto height = frames.size(2);
-  const auto width = frames.size(3);
+void write_interlaced_video(const torch::Tensor& chunk, AVFrame* buffer) {
+  const auto height = chunk.size(0);
+  const auto width = chunk.size(1);
+  const auto num_channels = chunk.size(2);
 
-  using namespace torch::indexing;
   size_t stride = width * num_channels;
-  for (int i = 0; i < num_frames; ++i) {
   // TODO: writable
   // https://ffmpeg.org/doxygen/4.1/muxing_8c_source.html#l00472
-    TORCH_CHECK(
-        av_frame_is_writable(os.src_frame),
-        "Internal Error: frame is not writable.");
-
-    // CHW -> HWC
-    auto chunk =
-        frames.index({i}).permute({1, 2, 0}).reshape({-1}).contiguous();
+  TORCH_INTERNAL_ASSERT(av_frame_is_writable(buffer), "frame is not writable.");
 
   uint8_t* src = chunk.data_ptr<uint8_t>();
-    uint8_t* dst = os.src_frame->data[0];
+  uint8_t* dst = buffer->data[0];
   for (int h = 0; h < height; ++h) {
     std::memcpy(dst, src, stride);
     src += width * num_channels;
-      dst += os.src_frame->linesize[0];
-    }
-    os.process_frame();
+    dst += buffer->linesize[0];
   }
 }
 
@@ -247,33 +223,24 @@ void write_interlaced_video(
 // H2:  UV ...  UV PAD ... PAD
 //
 void write_planar_video(
-    VideoOutputStream& os,
-    const torch::Tensor& frames,
+    const torch::Tensor& chunk,
+    AVFrame* buffer,
     int num_planes) {
-  const auto num_frames = frames.size(0);
-  const auto height = frames.size(2);
-  const auto width = frames.size(3);
+  const auto height = chunk.size(1);
+  const auto width = chunk.size(2);
 
-  using namespace torch::indexing;
-  for (int i = 0; i < num_frames; ++i) {
   // TODO: writable
   // https://ffmpeg.org/doxygen/4.1/muxing_8c_source.html#l00472
-    TORCH_CHECK(
-        av_frame_is_writable(os.src_frame),
-        "Internal Error: frame is not writable.");
+  TORCH_INTERNAL_ASSERT(av_frame_is_writable(buffer), "frame is not writable.");
 
   for (int j = 0; j < num_planes; ++j) {
-      auto chunk = frames.index({i, j}).contiguous();
-
-      uint8_t* src = chunk.data_ptr<uint8_t>();
-      uint8_t* dst = os.src_frame->data[j];
+    uint8_t* src = chunk.index({j}).data_ptr<uint8_t>();
+    uint8_t* dst = buffer->data[j];
     for (int h = 0; h < height; ++h) {
       memcpy(dst, src, width);
       src += width;
-        dst += os.src_frame->linesize[j];
-      }
+      dst += buffer->linesize[j];
     }
-    os.process_frame();
   }
 }
 
@@ -282,21 +249,33 @@ void write_planar_video(
 void VideoOutputStream::write_chunk(const torch::Tensor& frames) {
   enum AVPixelFormat fmt = static_cast<AVPixelFormat>(src_frame->format);
   validate_video_input(fmt, codec_ctx, frames);
+  const auto num_frames = frames.size(0);
 
 #ifdef USE_CUDA
   if (fmt == AV_PIX_FMT_CUDA) {
     fmt = codec_ctx->sw_pix_fmt;
     switch (fmt) {
       case AV_PIX_FMT_RGB0:
-      case AV_PIX_FMT_BGR0:
-        write_interlaced_video_cuda(*this, frames, true);
+      case AV_PIX_FMT_BGR0: {
+        auto chunks = frames.permute({0, 2, 3, 1}).contiguous(); // to NHWC
+        for (int i = 0; i < num_frames; ++i) {
+          write_interlaced_video_cuda(chunks.index({i}), src_frame, true);
+          process_frame();
+        }
         return;
+      }
       case AV_PIX_FMT_GBRP:
       case AV_PIX_FMT_GBRP16LE:
       case AV_PIX_FMT_YUV444P:
-      case AV_PIX_FMT_YUV444P16LE:
-        write_planar_video_cuda(*this, frames, av_pix_fmt_count_planes(fmt));
+      case AV_PIX_FMT_YUV444P16LE: {
+        auto chunks = frames.contiguous();
+        for (int i = 0; i < num_frames; ++i) {
+          write_planar_video_cuda(
+              chunks.index({i}), src_frame, av_pix_fmt_count_planes(fmt));
+          process_frame();
+        }
         return;
+      }
       default:
         TORCH_CHECK(
             false,
@@ -309,12 +288,23 @@ void VideoOutputStream::write_chunk(const torch::Tensor& frames) {
   switch (fmt) {
     case AV_PIX_FMT_GRAY8:
     case AV_PIX_FMT_RGB24:
-    case AV_PIX_FMT_BGR24:
-      write_interlaced_video(*this, frames);
+    case AV_PIX_FMT_BGR24: {
+      auto chunks = frames.permute({0, 2, 3, 1}).contiguous();
+      for (int i = 0; i < num_frames; ++i) {
+        write_interlaced_video(chunks.index({i}), src_frame);
+        process_frame();
+      }
       return;
-    case AV_PIX_FMT_YUV444P:
-      write_planar_video(*this, frames, av_pix_fmt_count_planes(fmt));
+    }
+    case AV_PIX_FMT_YUV444P: {
+      auto chunks = frames.contiguous();
+      for (int i = 0; i < num_frames; ++i) {
+        write_planar_video(
+            chunks.index({i}), src_frame, av_pix_fmt_count_planes(fmt));
+        process_frame();
+      }
       return;
+    }
     default:
       TORCH_CHECK(false, "Unexpected pixel format: ", av_get_pix_fmt_name(fmt));
   }