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• Anomalie #2139 : recherche et caractères accenctués

  27 juin 2011, par denisb -

  je ne reproduis pas ce comportement, ni avec firefox (5.0), ni avec chrome (12.0.742.100), ni avec safari (5.0.5). uniquement avec opera (11.11).

• Streaming different MP3 files using Ezstream and Icecast

  3 mai, par hh083

  I am trying to stream two MP3 files to Icecast using Ezstream and the stream should run in web browsers. The files I am testing with were downloaded as webm and converted to MP3 using ffmpeg. They have the same channels count, same bitrate and same sample rate but different duration.

  



  My setup : the Ezstream xml configuration file is set to stream MP3 and a program playlist is used to identify what is the next file to be streamed, and no encoders or decoders are used. When I start streaming I save the process ID of the Ezstream process (using the -p argument), and then I use the command kill -10 $(cat currentpid) with currentpid as the file containing the process ID so Ezstream executes the playlist program to get the next file name and skips the current file to play the next one. Basically I am just switching between 1.mp3 and 2.mp3.

  



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  The problem is that on Chrome web browser, when I switch between the two files the player (default HTML5 player) will suddenly stop (sometimes I can switch multiple times before it happens and sometimes it happens quickly) and the error PIPELINE_ERROR_DECODE is what I find when I access player.error in JavaScript. Although Firefox handles the change and continues the stream normally, I am convinced that Firefox here is the exception, that it is not a bug in Chrome (in my case), and that there is something wrong with my setup that needs to be fixed to support other browsers.

  



  Doing the same using mpv player, I get the following errors but the audio keeps streaming normally (sometimes it takes multiple switches before it happens just like in Chrome) :

  



  [ffmpeg/audio] mp3float: big_values too big
[ffmpeg/audio] mp3float: Error while decoding MPEG audio frame.
Error decoding audio.


  



  I tried using MP3 encoder and decoder I copied from the Ezstream example files (lame and madplay) but the problem still existed.

  



  I am not sure if the problem is basic and I cannot see it or it is more complicated. Also I do not have a problem if I need to use other format than MP3 to fix that issue, as long as that format is supported by Ezstream and Icecast.

  



  Thanks.

  


• Back on the Salty Track

  12 juin 2011, par Multimedia Mike — General

  After I posted about my initial encounter and frustration with Google’s Native Client (NaCl) SDK and took a deep breath, I realized that I achieved an important proof of concept— I successfully played music using the NaCl SDK audio output interface. Then I started taking a closer read through the (C-based set of) header files and realized I might be able to make a go of it after all. I had much better luck this time and managed to create a proper Native Client interface that allows for controlling playback, presenting metadata, and toggling individual voices (a fascinating tool for studying classic game music).

  I haven’t bothered to post the actual plugin because, really, what’s the point ? I started with NaCl SDK 0.3 which requires Chrome 12, which means terribly limited reach, even among Chrome users. At least, that was true when I restarted this little project. Chrome 12 was formally released this past week. Chrome development really does move at breakneck pace.

  Anyway, here is a static screenshot of what the plugin currently looks like :

  
  
  

  Not pretty, but it does the job.

  Dev Journal
  Various notes based on this outing :

  • Portability : I tested my plugin using Chrome 12 on 64-bit Windows, Mac, and Linux. Mac and Linux both work ; Windows does not.
  • Build System : SDK 0.3 is still lacking in its ability to compile .cpp files (instead of .cc files) ; necessary because libgme is C++ using .cpp files. This requires some build system modification.
  • Getting the interfaces : This is where I got tripped up the first time around. get_browser_interface() from their example actually refers to a parameter passed in through the PPP_InitializeModule() function. The SDK’s template generator renames this to get_browser().
  • Debugging : I feel unstoppable once I have a printf() mechanism available to me during development. To that end, console.log() from JavaScript outputs to Chrome’s built-in JavaScript console log while putting printf() statements in the actual NaCl plugin causes the messages to show up in /.xsession-errors on Linux/X.
  • Size Matters : The binaries generated with the NaCl 0.3 SDK are ridiculously huge. The basic "Hello World" example in C compiles to binaries that are 6.7 MB and 7.8 MB for the 32- and 64-bit builds, respectively. This made me apprehensive to build a full version of SaltyGME that contains all the bells and whistles offered by the library. However, all of the GME code compiled into the binary adds very little size. Curiously, the C++ version of "Hello World" only ranges from 1.8-2.0 MB for 32- and 64-bit. Is there some kind of C tax happening here ? Note that running ’strip’ on the resulting .nexe files (they’re ELF files, after all) brings the sizes down into the C++ range, but at the cost of causing them to not work (more specifically, not even load).
  • No Messaging : The NaCl SDK is supposed to have a messaging interface which allows the NaCl plugin to send asynchronous messages up to the hosting page. When I try to instantiate it, I get a NULL. I’m stuck with the alternative of polling from the JavaScript side to, e.g., determine when a song has finished loading via the network.

  That’s all I can think of for now. I may work on this a little more (I’d like to at least see some audio visualization). Maybe Google will enable NaCl per default sometime around Chrome 21 and this program will be ready for prime time by then.

  See Also :

  • My first attempt at this same project