addressing #3805: remove deprecated function call 3 (#3861)

* remove unused functions

* shut up annoying warnings via cast

* prabhat's comments

* Fixed clang format error
Co-authored-by: Prabhat Roy <prabhatroy@fb.com>

torchvision/csrc/io/decoder/audio_stream.cpp

@@ -7,13 +7,13 @@ namespace ffmpeg {
 
 namespace {
 bool operator==(const AudioFormat& x, const AVFrame& y) {
-  return x.samples == y.sample_rate && x.channels == y.channels &&
-      x.format == y.format;
+  return static_cast<int>(x.samples) == y.sample_rate &&
+      static_cast<int>(x.channels) == y.channels && x.format == y.format;
 }
 
 bool operator==(const AudioFormat& x, const AVCodecContext& y) {
-  return x.samples == y.sample_rate && x.channels == y.channels &&
-      x.format == y.sample_fmt;
+  return static_cast<int>(x.samples) == y.sample_rate &&
+      static_cast<int>(x.channels) == y.channels && x.format == y.sample_fmt;
 }
 
 AudioFormat& toAudioFormat(AudioFormat& x, const AVFrame& y) {

torchvision/csrc/io/decoder/decoder.cpp

@@ -196,8 +196,6 @@ int64_t Decoder::seekCallback(int64_t offset, int whence) {
 void Decoder::initOnce() {
   static std::once_flag flagInit;
   std::call_once(flagInit, []() {
-    av_register_all();
-    avcodec_register_all();
     avformat_network_init();
     // register ffmpeg lock manager
     av_lockmgr_register(&ffmpeg_lock);
@@ -397,10 +395,10 @@ bool Decoder::init(
 }
 
 bool Decoder::openStreams(std::vector<DecoderMetadata>* metadata) {
-  for (int i = 0; i < inputCtx_->nb_streams; i++) {
+  for (int i = 0; i < static_cast<int>(inputCtx_->nb_streams); i++) {
     // - find the corespondent format at params_.formats set
     MediaFormat format;
-    const auto media = inputCtx_->streams[i]->codec->codec_type;
+    const auto media = inputCtx_->streams[i]->codecpar->codec_type;
     if (!mapFfmpegType(media, &format.type)) {
       VLOG(1) << "Stream media: " << media << " at index " << i
               << " gets ignored, unknown type";