capturing CBC Radio from an internet stream

[Eric Battersby]

Hugh,

I wanted to do something similar to you, but your mail got me
thinking about, so I investigated further.

On Sun, 17 Feb 2008, D. Hugh Redelmeier wrote:

> This has taken a bit to figure out.  I hope some others find this
> information useful.
> 
> CBC Radio is streamed in two ways that I know about:
> 
> - ogg vorbis: experimental.  CBC Radio 1 in Toronto (only)
> 
> - mms stream containing .wma.  For each radio station.
> 
> See http://www.cbc.ca/listen/index.html
> 
> I would like to be able to report that ogg vorbis is the way to go,
> but there are two problems:
> 
> - every time try to capture an hour-long show, I find the stream is
>  broken off prematurely

I have not used ogg vorbis before.
I don't have any portable "MP3 players" that plays that format
and I've had about 10 players in the past.

I assume you are capturing it from:

   http://vorbis.nm.cbc.ca/cbcr1-toronto.ogg

How are you capturing it?

I tried this to grab a 15s segment:

   timeout -w 15 --
    wget -v -O tmp.ogg http://vorbis.nm.cbc.ca/cbcr1-toronto.ogg

   (see The Unix Prog Env. for a similar 'timeout')

I got a 36s segment OGG file.  It appears that some history is captured
in the stream also.
Could you break your shows into segments shorter than 1h, if 1h
is a problem?

I hadn't heard of 'mmsrip'.  That seems to be a good tool.
I haven't done much capturing, but I have used VLC (gui based), or this:

    mplayer.exe -dumpstream mms://somehost.com/somedirectory/somefile.wmv

For the record, when I tried this:

   mmsrip --delay=15 --output=cbc01.wma mms://wm.cbc.ca/cbcr1-toronto

I got a 15s wma file.  There may be about 0.5s of history.

> - I often want to record something that I found out about by coming in
>  on the middle.  In these cases, it is great to capture from a
>  station in a later timezone.

Why rely on alternate timezones which are arbitrary, instead of
a general solution?
Why not set up a daemon to capture the stream every N minutes,
along with some cleanup routines?

My example:
   ## 5m capture example:
   while true; do
     stamp=`/bin/date -u +'%Y%m%dT%H%M%SZ'`
     mmsrip --delay=300 --output=cbc01.$stamp.wma \
      mms://wm.cbc.ca/cbcr1-toronto
   done


> The output of mmsrip, at least in this case, is a .wma file.  But it
> is a bit malformed: it won't work in my mp3 players.  Two things do
> understand it:
> 
> - ffmpeg
> 
> - mplayer (because it uses the ffmpeg library)
> 
> It turns out that a null transcoding by ffmpeg can make the file work
> with my Creative Zen V!  ffmpeg has unconventional flags -- check the
> manpage.
>
>  ffmpeg -i captured.wma  -acodec copy nice.wma

Why bother with WMA format at all?  I had a player from several
years ago that played WMA files.  It does not play today's WMA files.
Convert it to MP3, so it will work in ALL MP3 players.
I know, the quality suffers slightly converting lossy to lossy,
but this is not high fidelity music we are talking about.


I tried this:

   $ ffmpeg -i cbc01.wma  cbc01.mp3
   $ file cbc01.mp3
   cbc01.mp3: MPEG ADTS, layer II, v1,  64 kBits, 44.1 kHz, Monaural

Unfortunately, it produced an MP2 file, not MP3.
I am not sure what is wrong.  MP2 is similar,
but may not be supported on all MP3 players.

Then I tried it in two steps; to WAV then to MP3:

   $ mplayer cbc01.wma   -ao pcm:file=cbc01.wav
   $ lame cbc01.wav # LAME 32bits version 3.97; produces cbc01.wav.mp3
   $ file   cbc01.wav.mp3
   cbc01.wav.mp3: MPEG ADTS, layer III, v1,  64 kBits, 44.1 kHz, Monaural

I listened to cbc01.mp3 and cbc01.wav.mp3 and did not notice any
difference in quality.
BTW, I encode music at 192 kbps cbr, and speech at 64 kbps cbr.

***

Other Notes:

I choose a 5m interval for files, which turned out to be convenient
for quickly accessing what I want to keep, by just hitting
the ">>|" button in VLC.

Also, I don't like MP3 files longer than 10m because
many MP3 players do not have a "very very fast-forward", nor
a rewind into the end of the previous track.

About your player:
You have a "Creative Zen V".  I used to have a "Creative Muvo 2GB White"
and it was one of the worst I have had; I had to return it.
Here is a list of the problems from my notes which may or may not
be relevant in your case:
   - will freeze up if there are symbolic links or shortcuts
   - will not play files deeper than 3 folder levels
     - that is unacceptable
   - must use predefined root folders
   - no way to skip current folder, except by skipping tracks
     or going to the menu and choosing skip folder
     (problem is that it doesn't keep track of where you were)
   - skipping folder always starts at the root of the default folder
   - pops and clicks were heard randomly, about 6 per hour
     (confirmed as systemic on some web forums)

--
Eric Battersby.
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