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authorHans Verkuil <hverkuil@xs4all.nl>2006-06-18 14:56:12 -0300
committerMauro Carvalho Chehab <mchehab@infradead.org>2006-06-25 02:05:22 -0300
commit54f577b7f46f48b8bea0bd5eb8c42d711b3e006f (patch)
treec091a214f10db8466feac1901ae3612fbbfd17c3 /Documentation/video4linux
parent18318e00040e0a5c783f6d79c136c2141b779dbd (diff)
downloadlinux-54f577b7f46f48b8bea0bd5eb8c42d711b3e006f.tar.bz2
V4L/DVB (4193): Update cx2341x fw encoding API doc.
Based on recent tests it turned out that some features are not implemented. This has now been documented. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Diffstat (limited to 'Documentation/video4linux')
-rw-r--r--Documentation/video4linux/cx2341x/fw-encoder-api.txt20
1 files changed, 18 insertions, 2 deletions
diff --git a/Documentation/video4linux/cx2341x/fw-encoder-api.txt b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
index 08ee9f5303f9..f74b0ae4a769 100644
--- a/Documentation/video4linux/cx2341x/fw-encoder-api.txt
+++ b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
@@ -100,13 +100,20 @@ Param[1]
Name CX2341X_ENC_SET_BIT_RATE
Enum 149/0x95
Description
- Assign average video stream bitrate.
+ Assign average video stream bitrate. Note on the last three params:
+ Param[3] and [4] seem to be always 0, param [5] doesn't seem to be used.
Param[0]
0=variable bitrate, 1=constant bitrate
Param[1]
bitrate in bits per second
Param[2]
peak bitrate in bits per second, divided by 400
+Param[3]
+ Mux bitrate in bits per second, divided by 400. May be 0 (default).
+Param[4]
+ Rate Control VBR Padding
+Param[5]
+ VBV Buffer used by encoder
-------------------------------------------------------------------------------
@@ -115,10 +122,11 @@ Enum 151/0x97
Description
Setup the GOP structure
Param[0]
- GOP size
+ GOP size (maximum is 34)
Param[1]
Number of B frames between the I and P frame, plus 1.
For example: IBBPBBPBBPBB --> GOP size: 12, number of B frames: 2+1 = 3
+ Note that GOP size must be a multiple of (B-frames + 1).
-------------------------------------------------------------------------------
@@ -241,6 +249,9 @@ Name CX2341X_ENC_SET_STREAM_TYPE
Enum 185/0xB9
Description
Assign stream type
+ Note: Transport stream is not working in recent firmwares.
+ And in older firmwares the timestamps in the TS seem to be
+ unreliable.
Param[0]
0=Program stream
1=Transport stream
@@ -278,6 +289,8 @@ Description
'01' Layer III
'00' Undefined
This discrepancy may indicate a possible error in the documentation.
+ Testing indicated that only Layer II is actually working, and that
+ the minimum bitrate should be 192 kbps.
Param[0]
Bitmask:
0:1 '00' 44.1Khz
@@ -313,6 +326,9 @@ Param[0]
'01'=JointStereo
'10'=Dual
'11'=Mono
+ Note: testing seems to indicate that Mono and possibly
+ JointStereo are not working (default to stereo).
+ Dual does work, though.
10:11 Mode Extension used in joint_stereo mode.
In Layer I and II they indicate which subbands are in