w64: fact guid support

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavformat/w64.c

@@ -29,6 +29,9 @@ const uint8_t ff_w64_guid_wave[16] = { 'w', 'a', 'v', 'e',
 const uint8_t ff_w64_guid_fmt [16] = { 'f', 'm', 't', ' ',
     0xF3, 0xAC, 0xD3, 0x11, 0x8C, 0xD1, 0x00, 0xC0, 0x4F, 0x8E, 0xDB, 0x8A };
 
+const uint8_t ff_w64_guid_fact[16] = { 'f', 'a', 'c', 't',
+    0xF3, 0xAC, 0xD3, 0x11, 0x8C, 0xD1, 0x00, 0xC0, 0x4F, 0x8E, 0xDB, 0x8A };
+
 const uint8_t ff_w64_guid_data[16] = { 'd', 'a', 't', 'a',
     0xF3, 0xAC, 0xD3, 0x11, 0x8C, 0xD1, 0x00, 0xC0, 0x4F, 0x8E, 0xDB, 0x8A };
 

libavformat/w64.h

@@ -24,6 +24,7 @@
 extern const uint8_t ff_w64_guid_riff[16];
 extern const uint8_t ff_w64_guid_wave[16];
 extern const uint8_t ff_w64_guid_fmt [16];
+extern const uint8_t ff_w64_guid_fact[16];
 extern const uint8_t ff_w64_guid_data[16];
 extern const uint8_t ff_w64_guid_summarylist[16];
 

libavformat/wavdec.c

@@ -610,6 +610,12 @@ static int w64_read_header(AVFormatContext *s)
             avio_skip(pb, FFALIGN(size, INT64_C(8)) - size);
 
             avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
+        } else if (!memcmp(guid, ff_w64_guid_fact, 16)) {
+            int64_t samples;
+
+            samples = avio_rl64(pb);
+            if (samples > 0)
+                st->duration = samples;
         } else if (!memcmp(guid, ff_w64_guid_data, 16)) {
             wav->data_end = avio_tell(pb) + size - 24;
 

libavformat/wavenc.c

@@ -263,6 +263,14 @@ static int w64_write_header(AVFormatContext *s)
         return ret;
     }
     end_guid(pb, start);
+
+    if (s->streams[0]->codec->codec_tag != 0x01 /* hence for all other than PCM */
+        && s->pb->seekable) {
+        start_guid(pb, ff_w64_guid_fact, &wav->fact_pos);
+        avio_wl64(pb, 0);
+        end_guid(pb, wav->fact_pos);
+    }
+
     start_guid(pb, ff_w64_guid_data, &wav->data);
 
     return 0;
@@ -280,8 +288,18 @@ static int w64_write_trailer(AVFormatContext *s)
         file_size = avio_tell(pb);
         avio_seek(pb, 16, SEEK_SET);
         avio_wl64(pb, file_size);
-        avio_seek(pb, file_size, SEEK_SET);
 
+        if (s->streams[0]->codec->codec_tag != 0x01) {
+            int64_t number_of_samples;
+
+            number_of_samples = av_rescale(wav->maxpts - wav->minpts + wav->last_duration,
+                                           s->streams[0]->codec->sample_rate * (int64_t)s->streams[0]->time_base.num,
+                                           s->streams[0]->time_base.den);
+            avio_seek(pb, wav->fact_pos + 24, SEEK_SET);
+            avio_wl64(pb, number_of_samples);
+        }
+
+        avio_seek(pb, file_size, SEEK_SET);
         avio_flush(pb);
     }