Merge "Allow edit list atom to appear earlier in the file"

media/libstagefright/MPEG4Extractor.cpp

@@ -463,6 +463,66 @@ sp<MetaData> MPEG4Extractor::getTrackMetaData(
         return NULL;
     }
 
+    int64_t duration;
+    int32_t samplerate;
+    if (track->has_elst && mHeaderTimescale != 0 &&
+            track->meta->findInt64(kKeyDuration, &duration) &&
+            track->meta->findInt32(kKeySampleRate, &samplerate)) {
+
+        track->has_elst = false;
+
+        if (track->elst_segment_duration > INT64_MAX) {
+            goto editlistoverflow;
+        }
+        int64_t segment_duration = track->elst_segment_duration;
+        int64_t media_time = track->elst_media_time;
+        int64_t halfscale = mHeaderTimescale / 2;
+
+        int64_t delay;
+        // delay = ((media_time * samplerate) + halfscale) / mHeaderTimescale;
+        if (__builtin_mul_overflow(media_time, samplerate, &delay) ||
+                __builtin_add_overflow(delay, halfscale, &delay) ||
+                (delay /= mHeaderTimescale, false) ||
+                delay > INT32_MAX ||
+                delay < INT32_MIN) {
+            goto editlistoverflow;
+        }
+        track->meta->setInt32(kKeyEncoderDelay, delay);
+
+        int64_t scaled_duration;
+        // scaled_duration = ((duration * mHeaderTimescale) + 500000) / 1000000;
+        if (__builtin_mul_overflow(duration, mHeaderTimescale, &scaled_duration) ||
+                __builtin_add_overflow(scaled_duration, 500000, &scaled_duration)) {
+            goto editlistoverflow;
+        }
+        scaled_duration /= 1000000;
+
+        int64_t segment_end;
+        int64_t padding;
+        if (__builtin_add_overflow(segment_duration, media_time, &segment_end) ||
+                __builtin_sub_overflow(scaled_duration, segment_end, &padding)) {
+            goto editlistoverflow;
+        }
+
+        if (padding < 0) {
+            // track duration from media header (which is what kKeyDuration is) might
+            // be slightly shorter than the segment duration, which would make the
+            // padding negative. Clamp to zero.
+            padding = 0;
+        }
+
+        int64_t paddingsamples;
+        // paddingsamples = ((padding * samplerate) + halfscale) / mHeaderTimescale;
+        if (__builtin_mul_overflow(padding, samplerate, &paddingsamples) ||
+                __builtin_add_overflow(paddingsamples, halfscale, &paddingsamples) ||
+                (paddingsamples /= mHeaderTimescale, false) ||
+                paddingsamples > INT32_MAX) {
+            goto editlistoverflow;
+        }
+        track->meta->setInt32(kKeyEncoderPadding, paddingsamples);
+    }
+    editlistoverflow:
+
     if ((flags & kIncludeExtensiveMetaData)
             && !track->includes_expensive_metadata) {
         track->includes_expensive_metadata = true;
@@ -989,6 +1049,7 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
                 track->skipTrack = false;
                 track->timescale = 0;
                 track->meta->setCString(kKeyMIMEType, "application/octet-stream");
+                track->has_elst = false;
             }
 
             off64_t stop_offset = *offset + chunk_size;
@@ -1055,6 +1116,10 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
         {
             *offset += chunk_size;
 
+            if (!mLastTrack) {
+                return ERROR_MALFORMED;
+            }
+
             // See 14496-12 8.6.6
             uint8_t version;
             if (mDataSource->readAt(data_offset, &version, 1) < 1) {
@@ -1069,8 +1134,6 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
             if (entry_count != 1) {
                 // we only support a single entry at the moment, for gapless playback
                 ALOGW("ignoring edit list with %d entries", entry_count);
-            } else if (mHeaderTimescale == 0) {
-                ALOGW("ignoring edit list because timescale is 0");
             } else {
                 off64_t entriesoffset = data_offset + 8;
                 uint64_t segment_duration;
@@ -1094,31 +1157,12 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
                     return ERROR_IO;
                 }
 
-                uint64_t halfscale = mHeaderTimescale / 2;
-                segment_duration = (segment_duration * 1000000 + halfscale)/ mHeaderTimescale;
-                media_time = (media_time * 1000000 + halfscale) / mHeaderTimescale;
-
-                int64_t duration;
-                int32_t samplerate;
-                if (!mLastTrack) {
-                    return ERROR_MALFORMED;
-                }
-                if (mLastTrack->meta->findInt64(kKeyDuration, &duration) &&
-                        mLastTrack->meta->findInt32(kKeySampleRate, &samplerate)) {
-
-                    int64_t delay = (media_time  * samplerate + 500000) / 1000000;
-                    mLastTrack->meta->setInt32(kKeyEncoderDelay, delay);
-
-                    int64_t paddingus = duration - (int64_t)(segment_duration + media_time);
-                    if (paddingus < 0) {
-                        // track duration from media header (which is what kKeyDuration is) might
-                        // be slightly shorter than the segment duration, which would make the
-                        // padding negative. Clamp to zero.
-                        paddingus = 0;
-                    }
-                    int64_t paddingsamples = (paddingus * samplerate + 500000) / 1000000;
-                    mLastTrack->meta->setInt32(kKeyEncoderPadding, paddingsamples);
-                }
+                // save these for later, because the elst atom might precede
+                // the atoms that actually gives us the duration and sample rate
+                // needed to calculate the padding and delay values
+                mLastTrack->has_elst = true;
+                mLastTrack->elst_media_time = media_time;
+                mLastTrack->elst_segment_duration = segment_duration;
             }
             break;
         }

media/libstagefright/include/MPEG4Extractor.h

@@ -82,6 +82,9 @@ private:
         sp<SampleTable> sampleTable;
         bool includes_expensive_metadata;
         bool skipTrack;
+        bool has_elst;
+        int64_t elst_media_time;
+        uint64_t elst_segment_duration;
     };
 
     Vector<SidxEntry> mSidxEntries;