Rockbox General > Rockbox General Discussion
Does Rockbox support '.cue' files for mp3's?
pabouk:
--- Quote from: saratoga on February 27, 2006, 03:44:38 PM ---To seek to track 5 in a que file, you have to load the ENTIRE file up to that point into memory. So if you want to play a 5MB track thats 50MB into a file, you have to load the entire 50MB to get at it. This is because cue (when used with audio) is somewhat of a hack and does not provide some sort of TOC function.
--- End quote ---
Why? If the format supports seeking (without decoding all the content) you just need to load the headers (as usually) and some parts to find the start of the track 5. When the format is CBR you do not even need to search for the track beginning, you load it directly.
This functionality is already implemented in Rockbock as the playback resume and I think it works well even with VBR formats (at least MP3 and OGG).
linuxstb:
--- Quote from: pabouk on February 28, 2006, 04:46:04 AM ---Why? If the format supports seeking (without decoding all the content) you just need to load the headers (as usually) and some parts to find the start of the track 5. When the format is CBR you do not even need to search for the track beginning, you load it directly.
This functionality is already implemented in Rockbock as the playback resume and I think it works well even with VBR formats (at least MP3 and OGG).
--- End quote ---
It can't work perfectly for MP3 for the simple reason that the individual MP3 frames do not contain a timestamp. So when you seek to a random point in the bitstream, you can only estimate where in the bitstream you are. This is why applications with good cuefile support such as foobar have to frame-walk the file.
Other formats, such as Ogg and FLAC, contain a timestamp in the header of each compressed frame - this is the key to accurate seeking. The MPEG-4 container (which could store MP3 streams if any software supported it) goes one step further by storing in the file header a full index containing the offset and length in both bytes and samples of every single frame in file - allowing extremely fast and accurate seeking.
rykos:
So once again we find ourselves let down by the worlds most 'popular' digital music format :(
Anyway, I have not seen foobar 'framewalking' a file, but would be interested to. Is this a processory-intensive operation for it to perform?
Is iRiver study mode feature also a problem with VBR mp3's?
My Winamp pulls it off without any problem - it just uses the cue list as a fast forwarding feature, rather like the study mode. It's instantaneous.
For anyone who's interested in using it, or more importantly, having a look at it for Rockbox purposes, the website for the plugin is http://www.guerillasoft.co.uk/mp3cue
Please note the first heading in the FAQ section of that page:
It's not accurate!
Yes it is (I think). For CBR mp3s, the accuracy is the same as for a wav file, and the same as for a CD. The problem comes with VBR mp3s. Winamp uses a fast, inaccurate method to seek positions within mp3s (otherwise it would take a second or so to seek...). This messes up the accuracy a bit, but it's not the fault of mp3cue (or Winamp, really).
A level of innaccuracy such as this is absolutely NO problem for me and would not be a problem for me in any Rockbox implementation.
rykos:
Guys, I really must insist that mp3cue is the way to go! :)
LinusN:
--- Quote from: rykos on February 28, 2006, 01:07:23 PM ---A level of innaccuracy such as this is absolutely NO problem for me and would not be a problem for me in any Rockbox implementation.
--- End quote ---
So you wouldn't be annoyed at all if you switched to the next track, and Rockbox started playing the last 10 seconds of the current one before playing the next?
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