don't return encoded bytes for now

Author: NicolasHug

src/torchcodec/decoders/_core/VideoDecoder.cpp

@@ -2145,7 +2145,7 @@ Encoder::Encoder(int sampleRate, std::string_view fileName)
   avcodec_parameters_from_context(avStream_->codecpar, avCodecContext_.get());
 }
 
-torch::Tensor Encoder::encode(const torch::Tensor& wf) {
+void Encoder::encode(const torch::Tensor& wf) {
   UniqueAVFrame avFrame(av_frame_alloc());
   TORCH_CHECK(avFrame != nullptr, "Couldn't allocate AVFrame.");
   avFrame->nb_samples = avCodecContext_->frame_size;
@@ -2222,9 +2222,6 @@ torch::Tensor Encoder::encode(const torch::Tensor& wf) {
       ffmpegRet == AVSUCCESS,
       "Error in: av_write_trailer",
       getFFMPEGErrorStringFromErrorCode(ffmpegRet));
-
-  // TODO handle writing to output uint8 tensor with AVIO logic.
-  return torch::empty({10});
 }
 
 void Encoder::encode_inner_loop(AutoAVPacket& autoAVPacket, AVFrame* avFrame) {

src/torchcodec/decoders/_core/VideoDecoder.h

@@ -597,7 +597,7 @@ class Encoder {
   // TODO doesn't make much sense to pass fileName and the wf tensor in 2
   // different calls. Same with sampleRate.
   Encoder(int sampleRate, std::string_view fileName);
-  torch::Tensor encode(const torch::Tensor& wf);
+  void encode(const torch::Tensor& wf);
 
  private:
   void encode_inner_loop(AutoAVPacket& autoAVPacket, AVFrame* avFrame);

src/torchcodec/decoders/_core/VideoDecoderOps.cpp

@@ -29,7 +29,7 @@ TORCH_LIBRARY(torchcodec_ns, m) {
       "torchcodec.decoders._core.ops", "//pytorch/torchcodec:torchcodec");
   m.def("create_from_file(str filename, str? seek_mode=None) -> Tensor");
   m.def("create_encoder(int sample_rate, str filename) -> Tensor");
-  m.def("encode(Tensor(a!) encoder, Tensor wf) -> Tensor");
+  m.def("encode(Tensor(a!) encoder, Tensor wf) -> ()");
   m.def(
       "create_from_tensor(Tensor video_tensor, str? seek_mode=None) -> Tensor");
   m.def("_convert_to_tensor(int decoder_ptr) -> Tensor");
@@ -151,9 +151,9 @@ at::Tensor create_encoder(int64_t sample_rate, std::string_view file_name) {
   return wrapEncoderPointerToTensor(std::move(uniqueEncoder));
 }
 
-at::Tensor encode(at::Tensor& encoder, const at::Tensor& wf) {
+void encode(at::Tensor& encoder, const at::Tensor& wf) {
   auto encoder_ = unwrapTensorToGetEncoder(encoder);
-  return encoder_->encode(wf);
+  encoder_->encode(wf);
 }
 
 at::Tensor create_from_tensor(