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NTSC recording
PostPosted: Tue Feb 21, 2006 6:51 pm Reply with quote
Joined: 20 Jan 2005
Posts: 43
Location: US

kernel 2.6.15-AS23-default

Recording NTSC works, but the visual quality looks like a 10th
generation copy using early VHS machines. :-(

I need a clue on which knobs to turn to get higher quality.

I've tried cranking vbitrate up from 4000 to 16000,
and lowering saturation and contrast. Lowering saturation
helps some, but it still looks low bandwidth.

I'm also getting stripes, about 10-20 degrees off from vertical.
If I reverse the field order (using the shift one scanline method),
I only get these stripes in the parts of the picture that are moving,
rather than the entire picture.

/app/bin/mencoder -oac lavc -ovc lavc \
-lavcopts acodec=mp2:abitrate=128:vcodec=mpeg4:vbitrate=16000:aspect=4/3 \
tv://${CHANNEL} \
-tv device=/dev/${DEVICE}:driver=v4l2:norm=0:outfmt=yuy2:width=640:height=480:\
forceaudio:audiorate=48000:chanlist=us-bcast:fps=29.97:volume=100 \

This later gets converted to DV format by ffmpeg, and shipped out firewire
to a camcorder, and then on to the TV via s-video.

I've also tried to get mencoder to output directly to DV format,
but no joy:

/app/bin/mencoder -tv \
adevice=/dev/dsp:amode=1:forceaudio:audiorate=48000:volume=100 \
-vf expand=720:480 \
tv://10 \
-of lavf -lavfopts format=dv \
-oac lavc -ovc lavc -lavcopts acodec=pcm_s16le:vcodec=dvvideo \
-o out.dv

Current format: BGR24
v4l2: current audio mode is : STEREO
audio block size too low, setting to 16384!
Selected channel: 10 (freq: 193.250)
[V] filefmt:9 fourcc:0x32595559 size:640x480 fps:29.97 ftime:=0.0334
Opening audio decoder: [pcm] Uncompressed PCM audio decoder
AUDIO: 48000 Hz, 2 ch, s16le, 1536.0 kbit/100.00% (ratio: 192000->192000)
Selected audio codec: [pcm] afm:pcm (Uncompressed PCM)
OK, exit
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1 (-1=autodetect) osd: 1
Opening video filter: [expand w=720 h=480]
Expand: 720 x 480, -1 ; -1 (-1=autodetect) osd: 0
Opening video decoder: [raw] RAW Uncompressed Video
VDec: vo config request - 640 x 480 (preferred csp: Packed YUY2)
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
VDec: using Packed YUY2 as output csp (no 0)
Movie-Aspect is undefined - no prescaling applied.
SwScaler: reducing / aligning filtersize 1 -> 4
SwScaler: reducing / aligning filtersize 1 -> 4
SwScaler: reducing / aligning filtersize 1 -> 1
SwScaler: reducing / aligning filtersize 9 -> 8

SwScaler: BICUBIC scaler, from Packed YUY2 to Planar YV12 using MMX2
videocodec: libavcodec (720x480 fourcc=69767664 [dvvi])
Selected video codec: [rawyuy2] vfm:raw (RAW YUY2)
Building audio filter chain for 48000Hz/2ch/s16le -> 48000Hz/2ch/s16le...
Writing AVI header...
[dv @ 0x85636dc]Can't initialize DV format!
Make sure that you supply exactly two streams:
video: 25fps or 29.97fps, audio: 2ch/48Khz/PCM
Forcing audio preload to 0, max pts correction to 0
New_Face failed. Maybe the font path is wrong.
Please supply the text font file (~/.mplayer/subfont.ttf).
subtitle font: load_sub_face failed.
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NTSC recording
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