lavf/riffenc: Set correct block align for mp2.

Rounding by Michael.

Fixes ticket #4565.

libavformat/riffenc.c

@@ -103,7 +103,7 @@ int ff_put_wav_header(AVIOContext *pb, AVCodecContext *enc, int flags)
     }
 
     if (enc->codec_id == AV_CODEC_ID_MP2) {
-        blkalign = frame_size;
+        blkalign = (144 * enc->bit_rate - 1)/enc->sample_rate + 1;
     } else if (enc->codec_id == AV_CODEC_ID_MP3) {
         blkalign = 576 * (enc->sample_rate <= (24000 + 32000)/2 ? 1 : 2);
     } else if (enc->codec_id == AV_CODEC_ID_AC3) {

tests/ref/lavf/asf

@@ -1,3 +1,3 @@
-1a8716a0358b8123c02557dfdf6c259b *./tests/data/lavf/lavf.asf
+76f131a5426f0ba5fc7409d1a1bbfdd7 *./tests/data/lavf/lavf.asf
 333585 ./tests/data/lavf/lavf.asf
 ./tests/data/lavf/lavf.asf CRC=0xf6340a10

tests/ref/lavf/avi

@@ -1,3 +1,3 @@
-07a29d329e7f07a4fd682145c3771995 *./tests/data/lavf/lavf.avi
+ab696052289d8dfea193e4cf94a94a6f *./tests/data/lavf/lavf.avi
 330814 ./tests/data/lavf/lavf.avi
 ./tests/data/lavf/lavf.avi CRC=0xec6c3c68

tests/ref/lavf/wtv

@@ -1,3 +1,3 @@
-b74b14ee41830aed90380bf6252dcfdb *./tests/data/lavf/lavf.wtv
+c5328b1c3e5fe70468c3f587c34ffd82 *./tests/data/lavf/lavf.wtv
 413696 ./tests/data/lavf/lavf.wtv
 ./tests/data/lavf/lavf.wtv CRC=0x71287e25