corrections to audio_set_id documentation

1 files changed, 9 insertions, 3 deletions

diff --git a/dvb-spec/dvbapi/audio.tex b/dvb-spec/dvbapi/audio.tex
index 8c5b4fe82..e81dd2f89 100644
--- a/dvb-spec/dvbapi/audio.tex
+++ b/dvb-spec/dvbapi/audio.tex
@@ -354,7 +354,12 @@ typedef uint16_t audioAttributes_t;
 \ifunction{AUDIO\_SET\_ID}{
   int ioctl(int fd, int request = AUDIO\_SET\_ID, int id);}{
   This ioctl selects which sub-stream is to be decoded if a program or
-  system stream is sent to the video device.
+  system stream is sent to the video device. If no audio stream type is set
+  the id has to be in [0xC0,0xDF] for MPEG sound, in [0x80,0x87] for
+  AC3 and in [0xA0,0xA7] for LPCM. More specifications may follow
+  for other stream types. If the stream type is set the id just
+  specifies the substream id of the audio stream and only the first 5
+  bits are recognized.
   }{
   int fd & File descriptor returned by a previous call to open().\\
   int request & Equals AUDIO\_SET\_ID for this command.\\
@@ -382,7 +387,7 @@ typedef uint16_t audioAttributes_t;
   int ioctl(fd, int request = AUDIO\_SET\_STREAMTYPE, int type);}{
   This ioctl tells the driver which kind of audio stream to expect.
   This is useful if the stream offers several audio sub-streams 
-  like MPEG2 audio and AC3.
+  like LPCM and AC3.
   }{
   int fd      & File descriptor returned by a previous call to open().\\
   int request & Equals AUDIO\_SET\_STREAMTYPE for this command.\\
@@ -395,7 +400,8 @@ typedef uint16_t audioAttributes_t;
 
 \ifunction{AUDIO\_SET\_EXT\_ID}{
   int ioctl(fd, int request = AUDIO\_SET\_EXT\_ID, int id);}{
-  This ioctl can be used to set the audio sub\_stream\_id for DVD playback
+  This ioctl can be used to set the extension id for MPEG streams in 
+  DVD playback. Only the first 3 bits are recognized. 
   }{
   int fd      & File descriptor returned by a previous call to open().\\
   int request & Equals AUDIO\_SET\_EXT\_ID for this command.\\