Rockbox Technical Forums

Rockbox Development => Starting Development and Compiling => Topic started by: toupee on May 09, 2007, 01:37:59 PM

Title: .flv codec for ipod
Post by: toupee on May 09, 2007, 01:37:59 PM
I would like to begin coding support for .flv and other flash formats for my ipod.
I personally can't hear the difference between .flv and .mp3.
And, I could store 2 to 3 times .flv songs as mp3's.
Would anyone like to help me?
Title: Re: .flv codec for ipod
Post by: saratoga on May 09, 2007, 02:50:12 PM
I would like to begin coding support for .flv and other flash formats for my ipod.
I personally can't hear the difference between .flv and .mp3.
And, I could store 2 to 3 times .flv songs as mp3's.
Would anyone like to help me?

flv uses mp3 for the audio.  Just demux the audio and listen to it directly in Rockbox.
Title: Re: .flv codec for ipod
Post by: toupee on May 09, 2007, 04:39:11 PM
I'm not an expert programmer. Could you explain that please  ::)
Title: Re: .flv codec for ipod
Post by: Chronon on May 09, 2007, 04:45:33 PM
demux = de-multiplex

In other words separate the multiplexed stream into its constituent channels and just record the audio stream as an mp3.  I have no idea about the practical details of how to do this, however.  I just know what mux/demux mean from electronics.
Title: Re: .flv codec for ipod
Post by: toupee on May 09, 2007, 04:55:56 PM
Let me clarify my question.

Im not talking about extracting the audio from flash video from youtube or something.

On my desktop, I converted my .mp3 songs to .flv. I dont want the mp3 format.
I would like to store and play my songs in .flv format on my ipod.
 
Title: Re: .flv codec for ipod
Post by: Llorean on May 09, 2007, 05:03:38 PM
FLV means "Flash Video" and is a video format.

Audio is muxed in, most often in MP3 format. If you converted your MP3s to FLV, it probably simply converted them to a lower bitrate MP3, then wasted space putting them in the FLV stream.
Title: Re: .flv codec for ipod
Post by: saratoga on May 09, 2007, 05:37:41 PM

On my desktop, I converted my .mp3 songs to .flv. I dont want the mp3 format.

FLV uses MP3 compression.  If you don't want MP3, use Ogg.  As it stands you've simply taken an MP3 and wrapped it in an FLV container.

I would like to store and play my songs in .flv format on my ipod.
 

And you can, provided you remove them from the FLV container first.  
Title: Re: .flv codec for ipod
Post by: toupee on May 09, 2007, 05:55:10 PM
Your right!

I just used a general mp3 converter to to convert to a lower bit rate, and I got the smaller file I was looking for!

This is great cause now I can store 2-3 times the number of songs on my ipod (and i cant hear the difference with my headphones).

How simple!
Thanks guys! your the best...
Title: Re: .flv codec for ipod
Post by: bluebrother on May 09, 2007, 06:09:10 PM
you could also use other formats like ogg, which usually gives smaller files at a comparable sound quality. This of course depends on what quality you want to have ;)
(just as a number, I usually have ogg files encoded with -q5 which results to an average of 160kbit, which is similar (IMO) to 192kbit mp3)
Title: Re: .flv codec for ipod
Post by: Rincewind on May 09, 2007, 07:44:18 PM
People at Hydrogenaudio forums have made a few listening tests and found out that with inexpensive headphones a bitrate of ~130 vbr with modern codecs is hard to distinguish from the original.
The difference between ogg, mp3 (lame) and other formats at the same bitrate was very small.
With better phones and a good ear, 160kbps (like bluebrother suggested) seems like a good idea.

If you chose mp3, I strongly suggest to rip your music with a vbr setting and joint stereo (v3 = ~170kbs for me, v6 should get you a bitrate of 120 on average).

But since you are transcoding, this doesn't matter much anyway, qualitywise.