[mythtv-users] recording radio as mp3 instead of mpg?

Nick Rout nick.rout at gmail.com
Wed Jul 23 01:09:47 UTC 2008


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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