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recording radio as mp3 instead of mpg?

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udovdh at xs4all

Jul 22, 2008, 10:59 AM

Post #1 of 11 (594 views)
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recording radio as mp3 instead of mpg?

Hello,

Can I configure MythTV somehow to record radio as mp3 file, instead of
mp3 inside an mpeg stream?
(I know I can dump the audio from the mpeg but I would like to skip that
step)

Anyone?

Kind regards,
Udo
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myth at dermanouelian

Jul 22, 2008, 11:17 AM

Post #2 of 11 (576 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Jul 22, 2008, at 10:59 AM, Udo van den Heuvel wrote:

> Hello,
>
> Can I configure MythTV somehow to record radio as mp3 file, instead of
> mp3 inside an mpeg stream?
> (I know I can dump the audio from the mpeg but I would like to skip
> that
> step)
>
> Anyone?

It depends on your capture card. If you're using a PVR-xxx card, then
no. It is an mpeg capture card and only captures mpeg streams. You'd
have to transcode the audio after capturing it. If it's some other
card that handles radio, then someone else would have to answer.

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jstembridge at gmail

Jul 22, 2008, 1:50 PM

Post #3 of 11 (568 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Tue, Jul 22, 2008 at 6:59 PM, Udo van den Heuvel <udovdh[at]xs4all.nl> wrote:
> Can I configure MythTV somehow to record radio as mp3 file, instead of
> mp3 inside an mpeg stream?
> (I know I can dump the audio from the mpeg but I would like to skip that
> step)

I assume you're talking about radio channels on dvb-t?

If so the audio is probably mp2 rather than mp3, at least that's
certainly the case here in the UK. Assuming this is the case for you
too you'll obviously have to transcode, there's a contrib script that
does that.

James.
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nick.rout at gmail

Jul 22, 2008, 4:35 PM

Post #4 of 11 (562 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Wed, Jul 23, 2008 at 8:50 AM, James Stembridge <jstembridge[at]gmail.com> wrote:
> On Tue, Jul 22, 2008 at 6:59 PM, Udo van den Heuvel <udovdh[at]xs4all.nl> wrote:
>> Can I configure MythTV somehow to record radio as mp3 file, instead of
>> mp3 inside an mpeg stream?
>> (I know I can dump the audio from the mpeg but I would like to skip that
>> step)
>
> I assume you're talking about radio channels on dvb-t?
>
> If so the audio is probably mp2 rather than mp3, at least that's
> certainly the case here in the UK. Assuming this is the case for you
> too you'll obviously have to transcode, there's a contrib script that
> does that.

One thing I am curious about, how different is an mp2 stream from an
mp3 stream? Is it backwards compatible? Can I change the file
extension from .mp2 to .mp3 and fool my ipod? If so you really only
need to demux the stream and change the extension.

Something to look at tonight :-)

(and yes the radio streams on dvb-s freeview in NZ are mp2 in an
mpeg-ts container)
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bradallenfuller at gmail

Jul 22, 2008, 4:41 PM

Post #5 of 11 (563 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Tue, Jul 22, 2008 at 4:35 PM, Nick Rout <nick.rout[at]gmail.com> wrote:
> On Wed, Jul 23, 2008 at 8:50 AM, James Stembridge <jstembridge[at]gmail.com> wrote:
>> On Tue, Jul 22, 2008 at 6:59 PM, Udo van den Heuvel <udovdh[at]xs4all.nl> wrote:
>>> Can I configure MythTV somehow to record radio as mp3 file, instead of
>>> mp3 inside an mpeg stream?
>>> (I know I can dump the audio from the mpeg but I would like to skip that
>>> step)
>>
>> I assume you're talking about radio channels on dvb-t?
>>
>> If so the audio is probably mp2 rather than mp3, at least that's
>> certainly the case here in the UK. Assuming this is the case for you
>> too you'll obviously have to transcode, there's a contrib script that
>> does that.
>
> One thing I am curious about, how different is an mp2 stream from an
> mp3 stream? Is it backwards compatible? Can I change the file
> extension from .mp2 to .mp3 and fool my ipod? If so you really only
> need to demux the stream and change the extension.

no. MP3, is actually a nickname for MPEG-1 Audio Layer 3.

Just google MPEG2 or MPEG-2

--
Brad Fuller
www.bradfuller.com
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nick.rout at gmail

Jul 22, 2008, 6:09 PM

Post #6 of 11 (562 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Wed, Jul 23, 2008 at 11:41 AM, Brad Fuller <bradallenfuller[at]gmail.com> wrote:
> On Tue, Jul 22, 2008 at 4:35 PM, Nick Rout <nick.rout[at]gmail.com> wrote:
>> On Wed, Jul 23, 2008 at 8:50 AM, James Stembridge <jstembridge[at]gmail.com> wrote:
>>> On Tue, Jul 22, 2008 at 6:59 PM, Udo van den Heuvel <udovdh[at]xs4all.nl> wrote:
>>>> Can I configure MythTV somehow to record radio as mp3 file, instead of
>>>> mp3 inside an mpeg stream?
>>>> (I know I can dump the audio from the mpeg but I would like to skip that
>>>> step)
>>>
>>> I assume you're talking about radio channels on dvb-t?
>>>
>>> If so the audio is probably mp2 rather than mp3, at least that's
>>> certainly the case here in the UK. Assuming this is the case for you
>>> too you'll obviously have to transcode, there's a contrib script that
>>> does that.
>>
>> One thing I am curious about, how different is an mp2 stream from an
>> mp3 stream? Is it backwards compatible? Can I change the file
>> extension from .mp2 to .mp3 and fool my ipod? If so you really only
>> need to demux the stream and change the extension.
>
> no. MP3, is actually a nickname for MPEG-1 Audio Layer 3.
>

Whats your point? mp2 is a nickname for MPEG-1 Audio Layer 2.
According to wikipedia:

"It took some 9 months and one extra layer of codec complexity to turn
MP2 into the well known MP3 format, by the introduction complementary
signal processing tools, such as an additional MDCT transform, entropy
coding and joint stereo mode (stereo intensity)."

Whether there is any backwards compatibility is not clear to me from
my reading so far. But if mp3 is another layer of complexity on top of
mp2 then it stands to reason that an mp3 decoder may be able to decode
and play an mp2 file.

> Just google MPEG2 or MPEG-2

we are not discussing mpeg2 except as a container. You will note my
suggestion was to demux the .mp2 audio stream from the mpeg2 broadcast
container and try playing the .mp2 stream in an mp3 player.

The fact that the Motion Picture Experts Group have their name in
almost everything to do with audio and video compression and
containers is the single biggest cause of confusion to newbies in this
area (IMHO, and not pointing at you!).
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bradallenfuller at gmail

Jul 22, 2008, 6:36 PM

Post #7 of 11 (553 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Tue, Jul 22, 2008 at 6:09 PM, Nick Rout <nick.rout[at]gmail.com> wrote:
> On Wed, Jul 23, 2008 at 11:41 AM, Brad Fuller <bradallenfuller[at]gmail.com> wrote:
>> On Tue, Jul 22, 2008 at 4:35 PM, Nick Rout <nick.rout[at]gmail.com> wrote:
>>> On Wed, Jul 23, 2008 at 8:50 AM, James Stembridge <jstembridge[at]gmail.com> wrote:
>>>> On Tue, Jul 22, 2008 at 6:59 PM, Udo van den Heuvel <udovdh[at]xs4all.nl> wrote:
>>>>> Can I configure MythTV somehow to record radio as mp3 file, instead of
>>>>> mp3 inside an mpeg stream?
>>>>> (I know I can dump the audio from the mpeg but I would like to skip that
>>>>> step)
>>>>
>>>> I assume you're talking about radio channels on dvb-t?
>>>>
>>>> If so the audio is probably mp2 rather than mp3, at least that's
>>>> certainly the case here in the UK. Assuming this is the case for you
>>>> too you'll obviously have to transcode, there's a contrib script that
>>>> does that.
>>>
>>> One thing I am curious about, how different is an mp2 stream from an
>>> mp3 stream? Is it backwards compatible? Can I change the file
>>> extension from .mp2 to .mp3 and fool my ipod? If so you really only
>>> need to demux the stream and change the extension.
>>
>> no. MP3, is actually a nickname for MPEG-1 Audio Layer 3.
>>
>
> Whats your point? mp2 is a nickname for MPEG-1 Audio Layer 2.

Hmm... I'm pretty sure it is one of the MPEG-1 Audio Layers (there
are 3 of them, I believe)

> According to wikipedia:
>
> "It took some 9 months and one extra layer of codec complexity to turn
> MP2 into the well known MP3 format, by the introduction complementary
> signal processing tools, such as an additional MDCT transform, entropy
> coding and joint stereo mode (stereo intensity)."
>
> Whether there is any backwards compatibility is not clear to me from
> my reading so far. But if mp3 is another layer of complexity on top of
> mp2 then it stands to reason that an mp3 decoder may be able to decode
> and play an mp2 file.

It's not another layer of complexity, as much as it is another
specification for an audio stream that can co-exist (if you will) with
mpeg1 and mpeg2 streams (and for that matter, other architectures.)

>
>> Just google MPEG2 or MPEG-2
>
> we are not discussing mpeg2 except as a container. You will note my
> suggestion was to demux the .mp2 audio stream from the mpeg2 broadcast
> container and try playing the .mp2 stream in an mp3 player.

Ok, google MPEG1. But, they'll get you to the same places.

I thought that you wanted to just rename the file to mp3 and see if
the iPod could play it. I suppose it could if the ipod decoder was
capable of picking the audio stream from the mpeg video file You
could certainly do it in linux and make an mp3 file to download.

Sorry for the confusion and the terse answer before.

You could visit the fraunhofer site to find out more about it:
http://www.iis.fraunhofer.de/EN/bf/amm/projects/index.jsp

Also: http://www.digital-audio.net/technical.shtml

brad
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bradallenfuller at gmail

Jul 22, 2008, 6:39 PM

Post #8 of 11 (553 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

Thinking back to your original post, I don't know what card you are
recording it on and I don't know if you are actually recording the
stream (it's analog and then you are digitizing it) or just copying
the stream (it's already digital and you are copying the stream). It
would make a difference on the file's contents once you captured the
program.
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udovdh at xs4all

Jul 23, 2008, 7:05 AM

Post #9 of 11 (527 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

Brad DerManouelian wrote:
>> Can I configure MythTV somehow to record radio as mp3 file, instead of
>> mp3 inside an mpeg stream?
>> (I know I can dump the audio from the mpeg but I would like to skip
>> that
>> step)
>>
>> Anyone?
>
> It depends on your capture card. If you're using a PVR-xxx card, then
> no.

It's a Terratec Cynergy 1200 DVB-T.

It is an mpeg capture card and only captures mpeg streams. You'd
> have to transcode the audio after capturing it. If it's some other
> card that handles radio, then someone else would have to answer.

I do not transcode but 'demux' the audio from teh mpeg that MythTV
creates. It appears to be already mp3.
HMm. No. (although XMMS palys it fine)
It is MPEG ADTS, layer II, v1, 160 kBits, 48 kHz, JntStereo.
So essentially mp2?

Well then, let me rephrase: how can I automagically demux the audio from
radio broadcasts?

Kind regards,
Udo

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kkuphal at gmail

Jul 23, 2008, 7:09 AM

Post #10 of 11 (527 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Wed, Jul 23, 2008 at 9:05 AM, Udo van den Heuvel <udovdh[at]xs4all.nl>
wrote:

> Brad DerManouelian wrote:
> >> Can I configure MythTV somehow to record radio as mp3 file, instead of
> >> mp3 inside an mpeg stream?
> >> (I know I can dump the audio from the mpeg but I would like to skip
> >> that
> >> step)
> >>
> >> Anyone?
> >
> > It depends on your capture card. If you're using a PVR-xxx card, then
> > no.
>
> It's a Terratec Cynergy 1200 DVB-T.
>
> It is an mpeg capture card and only captures mpeg streams. You'd
> > have to transcode the audio after capturing it. If it's some other
> > card that handles radio, then someone else would have to answer.
>
> I do not transcode but 'demux' the audio from teh mpeg that MythTV
> creates. It appears to be already mp3.
> HMm. No. (although XMMS palys it fine)
> It is MPEG ADTS, layer II, v1, 160 kBits, 48 kHz, JntStereo.
> So essentially mp2?
>
> Well then, let me rephrase: how can I automagically demux the audio from
> radio broadcasts?

Write a post-recording script that runs the same demux command you use.

Kevin

nick.rout at gmail

Jul 23, 2008, 3:26 PM

Post #11 of 11 (510 views)
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Re: recording radio as mp3 instead of mpg? [In reply to]

On Thu, Jul 24, 2008 at 2:09 AM, Kevin Kuphal <kkuphal[at]gmail.com> wrote:
> On Wed, Jul 23, 2008 at 9:05 AM, Udo van den Heuvel <udovdh[at]xs4all.nl>
> wrote:
>>
>> Brad DerManouelian wrote:
>> >> Can I configure MythTV somehow to record radio as mp3 file, instead of
>> >> mp3 inside an mpeg stream?
>> >> (I know I can dump the audio from the mpeg but I would like to skip
>> >> that
>> >> step)
>> >>
>> >> Anyone?
>> >
>> > It depends on your capture card. If you're using a PVR-xxx card, then
>> > no.
>>
>> It's a Terratec Cynergy 1200 DVB-T.
>>
>> It is an mpeg capture card and only captures mpeg streams. You'd
>> > have to transcode the audio after capturing it. If it's some other
>> > card that handles radio, then someone else would have to answer.
>>
>> I do not transcode but 'demux' the audio from teh mpeg that MythTV
>> creates. It appears to be already mp3.
>> HMm. No. (although XMMS palys it fine)
>> It is MPEG ADTS, layer II, v1, 160 kBits, 48 kHz, JntStereo.
>> So essentially mp2?
>>
>> Well then, let me rephrase: how can I automagically demux the audio from
>> radio broadcasts?
>
>
> Write a post-recording script that runs the same demux command you use.
>
> Kevin

See the very recent thread "Announce myth_dvbpodcast"
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