Date: Mon, 28 Aug 2006 13:56:31 +0100 From: Howard Jones <howie@thingy.com> To: Gary Kline <kline@tao.thought.org> Cc: andrew clarke <mail@ozzmosis.com>, "hackmiester \(Hunter Fuller\)" <hackmiester@hackmiester.com>, freebsd-questions@freebsd.org Subject: Re: taking many 198k mp3 files and converting them to 16k mp3 Message-ID: <44F2E7FF.6030402@thingy.com> In-Reply-To: <20060828015621.GA79317@thought.org> References: <20060827053654.GA60292@thought.org> <20060827060122.GA63679@ozzmosis.com> <20060827074946.GA60715@thought.org> <241DF2D9-F281-4AD5-90CE-BC23850360F2@hackmiester.com> <44F210BD.6040908@thingy.com> <20060828015621.GA79317@thought.org>
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Gary Kline wrote:
> Well, if/when you *do* try, please clue me in. --I'm too new to
> DVD's and tooo che--er, thrifty to buy a ten pack of blanks. I'm
> not sure that I have three hours of "favorites"; probably, but no
> more. Most of my favorite tunes are on tape--pre-recorded and
> hi-fidelity, but the problem is turnning analogue to digital.
Thrift isn't really an issue nowadays - you can get 50 DVD-Rs for about
$10-15 online. Cheap enough to use a few to experiement, in my opinion.
I did some experimenting last night, and got what seems to be a working
solution. I don't have a DVD burner where I am, so I haven't *actually*
burned one, but 2 software players (Apple's and Media Player Classic)
are both happy with the VIDEO_TS files. From my brief research, the
minimum bitrate for DVD audio is 32Khz, and there isn't a minimum for
the video, only a maximum. There is also a video-CD-like frame size of
352x480 for NTSC so you can reduced the video size further.
For my test audio file (2:12 song), I got:
2.2MB Original MP3 file - 192Kbit/sec 44.1Khz sample-rate joint stereo
3.3MB MP2 file - no changes apart from 44.1->48 resampling
0.5MB MP2 file - resampled to 48Khz, forced to mono and 32Kbit/sec
output stream
the 0.5MB file doesn't actually sound *that* bad for music - it's AM
radio quality. It would be fine for speech.
A 64Kbps video file to go with it is about 2.6MB, so the final 'DVD
file' is either 6.7M ('music' quality) or 4M ('voice' quality). DVD
authoring adds around 800K, but I don't believe this is per-chapter.
Assuming that it isn't, that's around 2400 minutes on a DVD-R (voice) or
1500 minutes (music), and it should be playable on any DVD player, since
it should be a full-spec DVD still.
Here's my notes on producing a disc. This is for an NTSC disc. For PAL,
you need to change 480 to 576 wherever it appears, add 'pal' instead of
'ntsc' to the dvdauthor line, and "-f 25" instead of "-f 30" in the
transcode line.
I'm no video expert, so I'm sure there are better ways to do this, but
this one worked for me!
Howie
######################################################################################
# Take the MP3 file, play it into toolame as 48Khz PCM data
# toolame reencodes as MP2 (for DVD) at 32khz (the minimum?) in mono
madplay -R48000 -b16 -o wave:- mytestfile.mp3 | toolame -s 48 -b 32 -a
-m m - mytestfile.mp2
# (take out the -b 32 and -a -m m if you want music quality)
# next, we'll produce a VERY low bitrate MPEG2 movie of the same length as
# the audio since we have to do *some* encoding here, we might as well make
# the static image be the title of the audio track.
# this is ALL ONE pipeline
ppmmake blue 352 480 | \
ppmlabel -x 50 -y 100 -text "This is the track name" | \
ppmtoy4m -S 420mpeg2 -r -v2 | \
transcode -x yuv4mpeg,mp3 -y mpeg2enc,null -o mytestfile -p
"mytestfile.mp3" \
-Z 352x480 -F "8,-b 64" -i /dev/stdin -g 352x480 --import_asr 2 -f
30 -m /dev/null
# So that's: make a blank blue image of the correct size for NTSC video
at the smallest size
# add a caption over it
# take that PPM file use it to stream frames into the video transcoder.
# (We only have one frame, so just repeat it)
# transcode takes that frame and encodes it as DVD-compatible 64kbps MPEG-2
# (normally for a DVD movie it would be more like 5000kpbs)
# we import an audio stream even though we aren't using it, so as to get
the
# right length. Otherwise we get a never-ending video stream :-)
# So now, there's a .m2v video stream, and a .mp2 audio stream, and we
need to
# multiplex them.
mplex -f 8 -o mytestfile.mpg mytestfile.m2v mytestfile.mp2
# *** repeat the above for each of your audio files. ***
# finally, we can make a simple DVD
dvdauthor -v ntsc+4:3+352x480 -a mp2+en+1ch+16bps -t -o testdvd
mytestfile.mpg
dvdauthor -T -o testdvd
# if you used 'music' quality encoding in toolame, then use 2ch instead
of 1ch here
# You should find a DVD structure (VIDEO_TS, AUDIO_TS) waiting in the
'testdvd' directory.
# you can specify multiple .mpg files on the command line, and each one
will
# become a chapter on the DVD
# FINALLY, to get a burnable ISO image:
mkisofs -dvd-video -o testdvd.iso testdvd
# and burn it to /dev/acd0:
growisofs -dvd-compat -Z /dev/acd0=testdvd.iso
# Ports used:
# sysutils/dvd+rw-tools (growisofs)
# sysutils/cdrtools (mkisofs - installed as a dependency of dvd+rw-tools)
# mjpegtools (mplex, y4m stuff)
# netpbm (ppmfile, ppmlabel)
# toolame (MPEG Layer II encoding)
# madplay (MP3 decoding)
# dvdauthor (final authoring)
# transcode (install this last, so it gets the mpeg2encode from mjpegtools)
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