Bug 1566389 - Trim the beginning and end of mp3 files, r=jya

Depends on D91772

Differential Revision: https://phabricator.services.mozilla.com/D91773

dom/media/platforms/ffmpeg/FFmpegAudioDecoder.cpp

@@ -5,6 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "FFmpegAudioDecoder.h"
+#include "FFmpegLog.h"
 #include "TimeUnits.h"
 #include "VideoUtils.h"
 #include "BufferReader.h"
@@ -21,9 +22,14 @@ FFmpegAudioDecoder<LIBAV_VER>::FFmpegAudioDecoder(FFmpegLibWrapper* aLib,
   if (aConfig.mCodecSpecificConfig && aConfig.mCodecSpecificConfig->Length()) {
     mExtraData = new MediaByteBuffer;
     mExtraData->AppendElements(*aConfig.mCodecSpecificConfig);
-    BufferReader reader(mExtraData->Elements(), mExtraData->Length());
-    mEncoderDelay = reader.ReadU32().unwrapOr(0);
-    mEncoderPadding = reader.ReadU32().unwrapOr(0);
+    if (mCodecID == AV_CODEC_ID_MP3) {
+      BufferReader reader(mExtraData->Elements(), mExtraData->Length());
+      mEncoderDelay = reader.ReadU32().unwrapOr(0);
+      mEncoderPadding = reader.ReadU32().unwrapOr(0);
+      FFMPEG_LOG("FFmpegAudioDecoder, found encoder delay (%" PRIu32
+                 ") and padding values (%" PRIu32 ") in extra data",
+                 mEncoderDelay, mEncoderPadding);
+    }
   }
 }
 
@@ -231,6 +237,24 @@ MediaResult FFmpegAudioDecoder<LIBAV_VER>::DoDecode(MediaRawData* aSample,
         return MediaResult(NS_ERROR_OUT_OF_MEMORY, __func__);
       }
 
+      bool trimmed = false;
+      if (mEncoderDelay) {
+        trimmed = true;
+        uint32_t toPop = std::min((uint32_t)mFrame->nb_samples, mEncoderDelay);
+        audio.PopFront(toPop * numChannels);
+        mFrame->nb_samples -= toPop;
+        mEncoderDelay -= toPop;
+      }
+
+      if (aSample->mEOS && mEncoderPadding) {
+        trimmed = true;
+        uint32_t toTrim =
+            std::min((uint32_t)mFrame->nb_samples, mEncoderPadding);
+        mEncoderPadding -= toTrim;
+        audio.PopBack(toTrim * numChannels);
+        mFrame->nb_samples = audio.Length() / numChannels;
+      }
+
       media::TimeUnit duration =
           FramesToTimeUnit(mFrame->nb_samples, samplingRate);
       if (!duration.IsValid()) {
@@ -248,7 +272,8 @@ MediaResult FFmpegAudioDecoder<LIBAV_VER>::DoDecode(MediaRawData* aSample,
       RefPtr<AudioData> data =
           new AudioData(samplePosition, pts, std::move(audio), numChannels,
                         samplingRate, mCodecContext->channel_layout);
-      MOZ_DIAGNOSTIC_ASSERT(duration == data->mDuration, "must be equal");
+      MOZ_DIAGNOSTIC_ASSERT(duration == data->mDuration || trimmed,
+                            "must be equal");
       aResults.AppendElement(std::move(data));
 
       pts = newpts;