mad-dev August 2001

mad-dev@lists.mars.org

7 participants
6 discussions

Seeking, frames and time
by Joe Drew 20 Sep '01

20 Sep '01

As part of mpg123 emulation, I've got to be able to seek in files and also report where in the file we're currently playing (in verbose mode, at least). Now, seeking isn't difficult: I just get the frame to which the user wants to seek, count the frames mad's passing to the header function, and return MAD_FLOW_IGNORE for every frame up to the one the user wants. However, the second one is a bit more difficult. I need to know (a) how many frames there are in any given file, and (b) how long the file is, in time. Now there is a solution similar to the above one: do an initial pass, returning MAD_FLOW_IGNORE for all the frames, and counting (a) the frames and (b) the total length of the file. Now that I'm looking in madplay, I notice that's somewhat along the lines of what's done in scan(). and calc() in madtime.c. Is this the only option? I assume it's not horribly inefficient, anyways, as it seems to be in use in madplay. Thanks again, -- Joe Drew <hoserhead(a)woot.net> <drew(a)debian.org> Please encrypt email sent to me.

2 3

sample accurate seeking with mad
by Andy Lo A Foe 28 Aug '01

28 Aug '01

Hi, I'm writing a player (http://www.alsaplayer.org) and currently use mpg123 for mp3 decoding purposes. I'm interested in adopting MAD because it is fully reentrant (right?). My question, is there sample accurate seeking possible in MAD? Thanks, Andy

2 1

MAD( Regarding the dynamic jumping to songs different location )
by Sadeesh Kumar 27 Aug '01

27 Aug '01

Hi, Rightnow i am trying to make one mp3 player for Compaq ipaq. For graphics, i am using Embedded Qt. I am using madplayer as mp3 engine. I have some issues in the slider scrolling support( In GUI, i want to provide one slider to jump to any part of the playing song like winamp ...). In libmad, when the song is playing, how can i jump to different differnt location and start to play from that location?. I find it, there is no direct easy interface to do this. If you can give some suggestion to me, it will be very help full. thanks in advance. with regards, sadeesh.

4 10

a high-level API question
by Joshua Haberman 22 Aug '01

22 Aug '01

There was one issue I ran into when implementing MP3 importing support for Audacity that I meant to ask about. It seems that when you pass the decoder data from the input callback, it tries to synthesize everything you give it. If the end of the buffer you passed ends in the middle of a frame, you get seams. Passing all the data to the decoder at once solves the problem, but that's not practical. As far as I can see, you can't get any metainformation (like the size of each frame) until you pass it data. Once you pass it data, you've probably misaligned the frame and produced garbage. What's the proper way to handle this situation? Joshua -- Joshua Haberman <joshua(a)haberman.com>

2 3

porting to VC++
by Joshua Haberman 22 Aug '01

22 Aug '01

Rob, I sent you an e-mail several weeks ago and have not heard back. Perhaps you didn't get it or deleted it, thinking it was spam. I've ported libmad to Visual C++ (with the intention of also having the port extend to the Mac) so that we can use mad in the cross-platform editor Audacity [0]. I've gotten it to compile, but I get several warnings, and I hoped you could tell me if they're important. I also hoped you might integrate the port into future releases of mad. The original message I sent you, which details the problems encountered and my solutions to them as well as the compiler warnings I got, can be found in the Audacity mailing list archive [1]. You can also find the port in Audacity's CVS [2]. Joshua [0] http://audacity.sourceforge.net [1] http://www.geocrawler.com/lists/3/SourceForge/11785/25/6377206/ [2] http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/audacity/lib-src/libmad/ -- Joshua Haberman <joshua(a)haberman.com>

2 1

libmad : example?
by mandor 08 Aug '01

08 Aug '01

Hi I'm planning to code a full-featured mp3 player and libmad seems great for this .. However, I didn't find much doc about using it... I want to be able to seek in the song : forward/rewind, etc ... How can I do this with libmad? Is there an example somewhere? Thx Mandor

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mad-dev August 2001