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>
diff --git a/Documentation/video4linux/cx2341x/fw-encoder-api.txt b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
index 08ee9f5..f74b0ae 100644
--- a/Documentation/video4linux/cx2341x/fw-encoder-api.txt
+++ b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
@@ -100,13 +100,20 @@
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 @@
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 @@
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 @@
'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 @@
'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
