AudioContentBlockSpec Tune-up

Summary:
This change improves AudioContentBlockSpec in the following ways:
- update the terminology to use "audio frame" as used in the audio industry, to designate a group of audio samples recorded at the same time, one sample by audio channel. With stereo audio, each audio frame has two audio samples, one per channel. We previously used "audio block", which is non-standard and easy to confuse with the audio content block.
- update constructors to require an AudioFormat, which allows use to...
- reorder parameters in AudioContentBlockSpec, so that all the parameters defining the format of the audio format comes first, followed by the frame spec (sample format, channel count, frame stride), then the sample frame rate, then the sample frame count, which is the most variable part of the definition, since in the same file you could easily have audio content blocks with different audio frame counts.

Reviewed By: perdoch

Differential Revision: D53338818

fbshipit-source-id: 6da17f9c3f91fee474b1404b78063bb273f2880b

csrc/utils/PyBuffer.cpp

@@ -59,7 +59,8 @@ const constexpr char* kImageSpecKeyFrameIndexKey = "key_frame_index";
 
 const constexpr char* kAudioSpecSampleCountKey = "sample_count";
 const constexpr char* kAudioSpecSampleFormatKey = "sample_format";
-const constexpr char* kAudioSpecSampleBlockStrideKey = "sample_block_stride";
+const constexpr char* kAudioSpecSampleBlockStrideKey = "sample_block_stride"; // deprecated
+const constexpr char* kAudioSpecSampleFrameStrideKey = "sample_frame_stride";
 const constexpr char* kAudioSpecChannelCountKey = "channel_count";
 const constexpr char* kAudioSpecSampleRateKey = "sample_rate";
 const constexpr char* kAudioSpecBufferSizeKey = "buffer_size";
@@ -137,7 +138,8 @@ void PyAudioContentBlockSpec::initAttributesMap() {
   if (attributesMap.empty()) {
     attributesMap[kAudioSpecSampleCountKey] = PYWRAP(getSampleCount());
     attributesMap[kAudioSpecSampleFormatKey] = PYWRAP(getSampleFormatAsString());
-    attributesMap[kAudioSpecSampleBlockStrideKey] = PYWRAP(getSampleBlockStride());
+    attributesMap[kAudioSpecSampleBlockStrideKey] = PYWRAP(getSampleFrameStride()); // deprecated
+    attributesMap[kAudioSpecSampleFrameStrideKey] = PYWRAP(getSampleFrameStride());
     attributesMap[kAudioSpecChannelCountKey] = PYWRAP(getChannelCount());
     attributesMap[kAudioSpecSampleRateKey] = PYWRAP(getSampleRate());
     attributesMap[kAudioSpecBufferSizeKey] = PYWRAP(getBlockSize());
@@ -284,7 +286,7 @@ py::buffer_info convertContentBlockBuffer(ContentBlockBuffer& block) {
   if (block.structuredArray && block.spec.getContentType() == vrs::ContentType::AUDIO) {
     const vrs::AudioContentBlockSpec& audioSpec = block.spec.audio();
     std::string sampleFormat;
-    uint32_t audioSampleStride = audioSpec.getSampleBlockStride();
+    uint32_t audioSampleStride = audioSpec.getSampleFrameStride();
     uint32_t audioSampleCount = audioSpec.getSampleCount();
     uint32_t channelCount = audioSpec.getChannelCount();
     uint32_t audioSampleByteSize = audioSpec.getBytesPerSample();
@@ -571,7 +573,10 @@ void pybind_buffer(py::module& m) {
           .def_property_readonly(
               kAudioSpecSampleFormatKey, &PyAudioContentBlockSpec::getSampleFormat)
           .def_property_readonly(
-              kAudioSpecSampleBlockStrideKey, &PyAudioContentBlockSpec::getSampleBlockStride)
+              kAudioSpecSampleBlockStrideKey,
+              &PyAudioContentBlockSpec::getSampleFrameStride) // deprecated
+          .def_property_readonly(
+              kAudioSpecSampleFrameStrideKey, &PyAudioContentBlockSpec::getSampleFrameStride)
           .def_property_readonly(
               kAudioSpecChannelCountKey, &PyAudioContentBlockSpec::getChannelCount)
           .def_property_readonly(kAudioSpecSampleRateKey, &PyAudioContentBlockSpec::getSampleRate)

csrc/utils/PyBuffer.h

@@ -143,8 +143,8 @@ class PyAudioContentBlockSpec {
     return spec_.getSampleFormatAsString();
   }
 
-  uint8_t getSampleBlockStride() const {
-    return spec_.getSampleBlockStride();
+  uint8_t getSampleFrameStride() const {
+    return spec_.getSampleFrameStride();
   }
 
   uint8_t getChannelCount() const {