ffm: do not write or read the audio sample format

libavformat/ffmdec.c

@@ -354,7 +354,6 @@ static int ffm_read_header(AVFormatContext *s)
             codec->sample_rate = avio_rb32(pb);
             codec->channels = avio_rl16(pb);
             codec->frame_size = avio_rl16(pb);
-            codec->sample_fmt = (int16_t) avio_rl16(pb);
             break;
         default:
             goto fail;

libavformat/ffmenc.c

@@ -170,7 +170,6 @@ static int ffm_write_header(AVFormatContext *s)
             avio_wb32(pb, codec->sample_rate);
             avio_wl16(pb, codec->channels);
             avio_wl16(pb, codec->frame_size);
-            avio_wl16(pb, codec->sample_fmt);
             break;
         default:
             return -1;

tests/ref/lavf/ffm

@@ -1,3 +1,3 @@
-0063b1b49d8641dcbf354092529a58a4 *./tests/data/lavf/lavf.ffm
+c5dcf5950031020864db57bbde0064df *./tests/data/lavf/lavf.ffm
 376832 ./tests/data/lavf/lavf.ffm
 ./tests/data/lavf/lavf.ffm CRC=0x38388ba1