Move seek() from wma.c to libasf since it's really ASF-specific.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26235 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 56 insertions, 1 deletions

diff --git a/apps/codecs/libasf/asf.c b/apps/codecs/libasf/asf.c
index 18503218b7..65d3fd8deb 100644
--- a/apps/codecs/libasf/asf.c
+++ b/apps/codecs/libasf/asf.c
@@ -376,3 +376,55 @@ int asf_get_timestamp(int *duration)
 
     return send_time;
 }
+
+/*entry point for seeks*/
+int seek(int ms, asf_waveformatex_t* wfx)
+{
+    int time, duration, delta, temp, count=0;
+
+    /*estimate packet number from bitrate*/
+    int initial_packet = ci->curpos/wfx->packet_size;
+    int packet_num = (((int64_t)ms)*(wfx->bitrate>>3))/wfx->packet_size/1000;
+    int last_packet = ci->id3->filesize / wfx->packet_size;
+
+    if (packet_num > last_packet) {
+        packet_num = last_packet;
+    }
+
+    /*calculate byte address of the start of that packet*/
+    int packet_offset = packet_num*wfx->packet_size;
+
+    /*seek to estimated packet*/
+    ci->seek_buffer(ci->id3->first_frame_offset+packet_offset);
+    temp = ms;
+    while (1)
+    {
+        /*for very large files it can be difficult and unimportant to find the exact packet*/
+        count++;
+
+        /*check the time stamp of our packet*/
+        time = asf_get_timestamp(&duration);
+        DEBUGF("seeked to %d ms with duration %d\n", time, duration);
+
+        if (time < 0) {
+            /*unknown error, try to recover*/
+            DEBUGF("UKNOWN SEEK ERROR\n");
+            ci->seek_buffer(ci->id3->first_frame_offset+initial_packet*wfx->packet_size);
+            /*seek failed so return time stamp of the initial packet*/
+            return asf_get_timestamp(&duration);
+        }
+
+        if ((time+duration>=ms && time<=ms) || count > 10) {
+            DEBUGF("Found our packet! Now at %d packet\n", packet_num);
+            return time;
+        } else {
+            /*seek again*/
+            delta = ms-time;
+            /*estimate new packet number from bitrate and our current position*/
+            temp += delta;
+            packet_num = ((temp/1000)*(wfx->bitrate>>3) - (wfx->packet_size>>1))/wfx->packet_size;  //round down!
+            packet_offset = packet_num*wfx->packet_size;
+            ci->seek_buffer(ci->id3->first_frame_offset+packet_offset);
+        }
+    }
+}
diff --git a/apps/codecs/libasf/asf.h b/apps/codecs/libasf/asf.h
index c15bf4edec..9592618997 100644
--- a/apps/codecs/libasf/asf.h
+++ b/apps/codecs/libasf/asf.h
@@ -32,7 +32,8 @@ struct asf_waveformatex_s {
     uint16_t blockalign;
     uint16_t bitspersample;
     uint16_t datalen;
-    uint8_t data[6];
+    uint16_t numpackets;
+    uint8_t data[18];
 };
 typedef struct asf_waveformatex_s asf_waveformatex_t;
 
@@ -41,5 +42,7 @@ int asf_read_packet(uint8_t** audiobuf, int* audiobufsize, int* packetlength,
                     
 int asf_get_timestamp(int *duration);
 
+int seek(int ms, asf_waveformatex_t* wfx);
+
 
 #endif /* _ASF_H */