Handle AVCodec fields deprecated in FFmpeg 7 (#898)

Co-authored-by: Daniel Flores <[email protected]>

Author: Dan-Flores

src/torchcodec/_core/Encoder.cpp

@@ -33,21 +33,22 @@ torch::Tensor validateSamples(const torch::Tensor& samples) {
 }
 
 void validateSampleRate(const AVCodec& avCodec, int sampleRate) {
-  if (avCodec.supported_samplerates == nullptr) {
+  const int* supportedSampleRates = getSupportedSampleRates(avCodec);
+  if (supportedSampleRates == nullptr) {
     return;
   }
 
-  for (auto i = 0; avCodec.supported_samplerates[i] != 0; ++i) {
-    if (sampleRate == avCodec.supported_samplerates[i]) {
+  for (auto i = 0; supportedSampleRates[i] != 0; ++i) {
+    if (sampleRate == supportedSampleRates[i]) {
       return;
     }
   }
   std::stringstream supportedRates;
-  for (auto i = 0; avCodec.supported_samplerates[i] != 0; ++i) {
+  for (auto i = 0; supportedSampleRates[i] != 0; ++i) {
     if (i > 0) {
       supportedRates << ", ";
     }
-    supportedRates << avCodec.supported_samplerates[i];
+    supportedRates << supportedSampleRates[i];
   }
 
   TORCH_CHECK(
@@ -73,27 +74,30 @@ static const std::vector<AVSampleFormat> preferredFormatsOrder = {
     AV_SAMPLE_FMT_U8};
 
 AVSampleFormat findBestOutputSampleFormat(const AVCodec& avCodec) {
+  const AVSampleFormat* supportedSampleFormats =
+      getSupportedOutputSampleFormats(avCodec);
+
   // Find a sample format that the encoder supports. We prefer using FLT[P],
   // since this is the format of the input samples. If FLTP isn't supported
   // then we'll need to convert the AVFrame's format. Our heuristic is to encode
   // into the format with the highest resolution.
-  if (avCodec.sample_fmts == nullptr) {
+  if (supportedSampleFormats == nullptr) {
     // Can't really validate anything in this case, best we can do is hope that
     // FLTP is supported by the encoder. If not, FFmpeg will raise.
     return AV_SAMPLE_FMT_FLTP;
   }
 
   for (AVSampleFormat preferredFormat : preferredFormatsOrder) {
-    for (int i = 0; avCodec.sample_fmts[i] != -1; ++i) {
-      if (avCodec.sample_fmts[i] == preferredFormat) {
+    for (int i = 0; supportedSampleFormats[i] != -1; ++i) {
+      if (supportedSampleFormats[i] == preferredFormat) {
         return preferredFormat;
       }
     }
   }
   // We should always find a match in preferredFormatsOrder, so we should always
   // return earlier. But in the event that a future FFmpeg version defines an
   // additional sample format that isn't in preferredFormatsOrder, we fallback:
-  return avCodec.sample_fmts[0];
+  return supportedSampleFormats[0];
 }
 
 } // namespace

src/torchcodec/_core/FFMPEGCommon.cpp

@@ -56,6 +56,46 @@ int64_t getDuration(const UniqueAVFrame& avFrame) {
 #endif
 }
 
+const int* getSupportedSampleRates(const AVCodec& avCodec) {
+  const int* supportedSampleRates = nullptr;
+#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(61, 13, 100)
+  int numSampleRates = 0;
+  int ret = avcodec_get_supported_config(
+      nullptr,
+      &avCodec,
+      AV_CODEC_CONFIG_SAMPLE_RATE,
+      0,
+      reinterpret_cast<const void**> & supportedSampleRates,
+      &numSampleRates);
+  if (ret < 0 || supportedSampleRates == nullptr) {
+    TORCH_CHECK(false, "Couldn't get supported sample rates from encoder.");
+  }
+#else
+  supportedSampleRates = avCodec.supported_samplerates;
+#endif
+  return supportedSampleRates;
+}
+
+const AVSampleFormat* getSupportedOutputSampleFormats(const AVCodec& avCodec) {
+  const AVSampleFormat* supportedSampleFormats = nullptr;
+#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(61, 13, 100) // FFmpeg >= 7
+  int numSampleFormats = 0;
+  int ret = avcodec_get_supported_config(
+      nullptr,
+      &avCodec,
+      AV_CODEC_CONFIG_SAMPLE_FORMAT,
+      0,
+      reinterpret_cast<const void**> & supportedSampleFormats,
+      &numSampleFormats);
+  if (ret < 0 || supportedSampleFormats == nullptr) {
+    TORCH_CHECK(false, "Couldn't get supported sample formats from encoder.");
+  }
+#else
+  supportedSampleFormats = avCodec.sample_fmts;
+#endif
+  return supportedSampleFormats;
+}
+
 int getNumChannels(const UniqueAVFrame& avFrame) {
 #if LIBAVFILTER_VERSION_MAJOR > 8 || \
     (LIBAVFILTER_VERSION_MAJOR == 8 && LIBAVFILTER_VERSION_MINOR >= 44)
@@ -109,7 +149,31 @@ void setDefaultChannelLayout(UniqueAVFrame& avFrame, int numChannels) {
 }
 
 void validateNumChannels(const AVCodec& avCodec, int numChannels) {
-#if LIBAVFILTER_VERSION_MAJOR > 7 // FFmpeg > 4
+#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(61, 13, 100) // FFmpeg >= 7
+  std::stringstream supportedNumChannels;
+  const AVChannelLayout* supported_layouts = nullptr;
+  int num_layouts = 0;
+  int ret = avcodec_get_supported_config(
+      nullptr,
+      &avCodec,
+      AV_CODEC_CONFIG_CHANNEL_LAYOUT,
+      0,
+      reinterpret_cast<const void**> & supported_layouts,
+      &num_layouts);
+  if (ret < 0 || supported_layouts == nullptr) {
+    TORCH_CHECK(false, "Couldn't get supported channel layouts from encoder.");
+    return;
+  }
+  for (int i = 0; supported_layouts[i].nb_channels != 0; ++i) {
+    if (i > 0) {
+      supportedNumChannels << ", ";
+    }
+    supportedNumChannels << supported_layouts[i].nb_channels;
+    if (numChannels == supported_layouts[i].nb_channels) {
+      return;
+    }
+  }
+#elif LIBAVFILTER_VERSION_MAJOR > 7 // FFmpeg > 4
   if (avCodec.ch_layouts == nullptr) {
     // If we can't validate, we must assume it'll be fine. If not, FFmpeg will
     // eventually raise.
@@ -131,7 +195,7 @@ void validateNumChannels(const AVCodec& avCodec, int numChannels) {
     }
     supportedNumChannels << avCodec.ch_layouts[i].nb_channels;
   }
-#else
+#else // FFmpeg <= 4
   if (avCodec.channel_layouts == nullptr) {
     // can't validate, same as above.
     return;

src/torchcodec/_core/FFMPEGCommon.h

@@ -162,6 +162,9 @@ std::string getFFMPEGErrorStringFromErrorCode(int errorCode);
 // support.
 int64_t getDuration(const UniqueAVFrame& frame);
 
+const int* getSupportedSampleRates(const AVCodec& avCodec);
+const AVSampleFormat* getSupportedOutputSampleFormats(const AVCodec& avCodec);
+
 int getNumChannels(const UniqueAVFrame& avFrame);
 int getNumChannels(const UniqueAVCodecContext& avCodecContext);