Use audio sample rate as timescale

This will avoid rounding errors during conversion.
In the dump files, the timestamps are now exactly same
as those from input file.

PiperOrigin-RevId: 787040930

Author: SheenaChhabra

libraries/muxer/src/main/java/androidx/media3/muxer/Track.java

@@ -109,8 +109,7 @@ public void writeSampleData(ByteBuffer byteBuffer, BufferInfo bufferInfo) {
   }
 
   public int videoUnitTimebase() {
-    return MimeTypes.isAudio(format.sampleMimeType)
-        ? 48_000 // TODO: b/270583563 - Update these with actual values from mediaFormat.
-        : 90_000;
+    // TODO: b/270583563 - Use frame rate for video tracks.
+    return MimeTypes.isAudio(format.sampleMimeType) ? format.sampleRate : 90_000;
   }
 }

libraries/test_data/src/test/assets/muxerdumps/sample_av1.mp4.dump

@@ -1,10 +1,10 @@
 seekMap:
   isSeekable = true
-  duration = 1045300
+  duration = 1044900
   getPosition(0) = [[timeUs=0, position=400052]]
   getPosition(1) = [[timeUs=0, position=400052]]
-  getPosition(522650) = [[timeUs=0, position=400052]]
-  getPosition(1045300) = [[timeUs=0, position=400052]]
+  getPosition(522450) = [[timeUs=0, position=400052]]
+  getPosition(1044900) = [[timeUs=0, position=400052]]
 numberOfTracks = 2
 track 0:
   total output bytes = 69084
@@ -149,9 +149,9 @@ track 0:
 track 1:
   total output bytes = 9312
   sample count = 45
-  track duration = 1045300
+  track duration = 1044900
   format 0:
-    averageBitrate = 71267
+    averageBitrate = 71295
     peakBitrate = 71295
     id = 2
     containerMimeType = video/mp4
@@ -169,179 +169,179 @@ track 1:
     flags = 1
     data = length 21, hash 77102128
   sample 1:
-    time = 66229
+    time = 66219
     flags = 1
     data = length 17, hash BA75F5D4
   sample 2:
-    time = 89458
+    time = 89439
     flags = 1
     data = length 582, hash B5064B53
   sample 3:
-    time = 112687
+    time = 112659
     flags = 1
     data = length 218, hash 46000EEF
   sample 4:
-    time = 135916
+    time = 135879
     flags = 1
     data = length 206, hash 7B12EC38
   sample 5:
-    time = 159145
+    time = 159099
     flags = 1
     data = length 215, hash C05E2F91
   sample 6:
-    time = 182375
+    time = 182319
     flags = 1
     data = length 217, hash 1E457BBF
   sample 7:
-    time = 205604
+    time = 205539
     flags = 1
     data = length 195, hash DFD6F480
   sample 8:
-    time = 228833
+    time = 228759
     flags = 1
     data = length 198, hash 2BC702E
   sample 9:
-    time = 252062
+    time = 251979
     flags = 1
     data = length 216, hash ED964B3D
   sample 10:
-    time = 275291
+    time = 275199
     flags = 1
     data = length 204, hash DAF6FDC6
   sample 11:
-    time = 298520
+    time = 298419
     flags = 1
     data = length 205, hash D249FD76
   sample 12:
-    time = 321750
+    time = 321639
     flags = 1
     data = length 200, hash C8F844E4
   sample 13:
-    time = 344979
+    time = 344859
     flags = 1
     data = length 196, hash FDD0CA03
   sample 14:
-    time = 368208
+    time = 368079
     flags = 1
     data = length 196, hash E4E3A7B0
   sample 15:
-    time = 391437
+    time = 391299
     flags = 1
     data = length 207, hash 157773E3
   sample 16:
-    time = 414666
+    time = 414519
     flags = 1
     data = length 207, hash C9F46F0F
   sample 17:
-    time = 437895
+    time = 437739
     flags = 1
     data = length 210, hash 127AC739
   sample 18:
-    time = 461125
+    time = 460959
     flags = 1
     data = length 217, hash B2649830
   sample 19:
-    time = 484354
+    time = 484179
     flags = 1
     data = length 188, hash 4D280759
   sample 20:
-    time = 507583
+    time = 507399
     flags = 1
     data = length 205, hash EAE6D6AD
   sample 21:
-    time = 530812
+    time = 530619
     flags = 1
     data = length 226, hash BDD0EC44
   sample 22:
-    time = 554041
+    time = 553839
     flags = 1
     data = length 199, hash 60C719A2
   sample 23:
-    time = 577270
+    time = 577058
     flags = 1
     data = length 215, hash EDDE842F
   sample 24:
-    time = 600500
+    time = 600278
     flags = 1
     data = length 201, hash D17187B
   sample 25:
-    time = 623729
+    time = 623498
     flags = 1
     data = length 217, hash 58DD698C
   sample 26:
-    time = 646958
+    time = 646718
     flags = 1
     data = length 202, hash 5168D405
   sample 27:
-    time = 670187
+    time = 669938
     flags = 1
     data = length 194, hash 7139AF8
   sample 28:
-    time = 693416
+    time = 693158
     flags = 1
     data = length 203, hash F775D9ED
   sample 29:
-    time = 716645
+    time = 716378
     flags = 1
     data = length 200, hash 774C5045
   sample 30:
-    time = 739875
+    time = 739598
     flags = 1
     data = length 211, hash ED3C6FBC
   sample 31:
-    time = 763104
+    time = 762818
     flags = 1
     data = length 205, hash FC4754A9
   sample 32:
-    time = 786333
+    time = 786038
     flags = 1
     data = length 216, hash 72F4AF29
   sample 33:
-    time = 809562
+    time = 809258
     flags = 1
     data = length 204, hash 1AF98D40
   sample 34:
-    time = 832791
+    time = 832478
     flags = 1
     data = length 200, hash E0004171
   sample 35:
-    time = 856020
+    time = 855698
     flags = 1
     data = length 215, hash B413079A
   sample 36:
-    time = 879250
+    time = 878918
     flags = 1
     data = length 211, hash 107CEE52
   sample 37:
-    time = 902479
+    time = 902138
     flags = 1
     data = length 214, hash 1E588A0D
   sample 38:
-    time = 925708
+    time = 925358
     flags = 1
     data = length 210, hash 84E5BBBD
   sample 39:
-    time = 948937
+    time = 948578
     flags = 1
     data = length 211, hash 32D7ACAB
   sample 40:
-    time = 972166
+    time = 971798
     flags = 1
     data = length 201, hash 1567F919
   sample 41:
-    time = 995395
+    time = 995018
     flags = 1
     data = length 196, hash 2F050463
   sample 42:
-    time = 1018625
+    time = 1018238
     flags = 1
     data = length 215, hash 4BDD9C81
   sample 43:
-    time = 1041854
+    time = 1041458
     flags = 1
     data = length 242, hash DD6FD967
   sample 44:
-    time = 1065083
+    time = 1064678
     flags = 536870913
     data = length 184, hash DAFC330D
 tracksEnded = true