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• downsizing multiple mpg files using ffmpeg.exe

  14 septembre 2022, par user2799077

  I'm using ffmpeg.exe to process screen captures for a demo using MS Game Bar. Game Bar captures at a high frame rate at high resolution and the files are very large.

  


  Using ffmpeg.exe I can process the files using :

  


  ffmpeg.exe -i file.mpg file_l.mpg

  


  And all is good but I'd like to create a bat file so I can do half a dozen or any in a folder all at once.

  


  My Windows bat skills are poor and I've been trying to get it to work using something like this without success :

  


  for %%f in (*.mp4) do (
  ren %%~nf%%~xf !fileNum!%%~xf
  set/a fileNum += 1


  


  Can anyone help please

  


• Chiptune Database and API

  14 septembre 2012, par Multimedia Mike — General

  So I set out to create a website that allows people to easily listen to video game music directly through their web browser. I succeeded in that goal. However, I must admit that the project has limited appeal since the web player is delivered via Chrome’s Native Client technology, somewhat limiting its audience. I’m not certain if anyone really expects NaCl to take off in any serious way, but I still have a few other projects in mind.

  I recently realized that, as a side effect of this project, I accidentally created something of significant value to fans of old video games and associated music– a searchable database of chiptune music and metadata. To my knowledge, no one else has endeavored to create such a thing. I figured that I might as well make the database easily accessible with an API and see where it leads.

  To that end, I created 2 API entry points. First, there is the search API located at http://gamemusic.multimedia.cx/api/search/. This can be exercised by ending the URL with a URL-encoded search string, e.g. : http://gamemusic.multimedia.cx/api/search/super+mario. This returns JSON data containing an array of results in decreasing order of relevance. Each result has a game title, database ID, media URL, system type, and an SHA-1 hash. This is the same API that the site’s own search page uses.

  The database ID can be plugged into http://gamemusic.multimedia.cx/api/metadata/ to retrieve the song’s metadata in JSON format. E.g., the ID for Super Mario Bros. 3 on the NES is 161 : http://gamemusic.multimedia.cx/api/metadata/161.

  I recently read an article about sins against true RESTful API principles which led me to believe I’m almost certainly doing this web API stuff wrong. I don’t think it’s a huge deal, though, since I don’t think anyone actually listens to chiptunes any more. But if there are offline chiptune music players that are still in service and actively maintained, perhaps the authors would like to implement this API. It would require some type of HTTP networking library, a JSON parser, the embedded XZ decoder, and some new code to parse through my .gamemusic and .psfarchive formats.

  This database could be a significant value-add to chiptune playback software, and could help people experience classic game music much more easily.

• Zlib vs. XZ on 2SF

  21 juillet 2012, par Multimedia Mike — General, psf, saltygme, xz, zlib

  I recently released my Game Music Appreciation website. It allows users to play an enormous range of video game music directly in their browsers. To do this, the site has to host the music. And since I’m a compression bore, I have to know how small I can practically make these music files. I already published the results of my effort to see if XZ could beat RAR (RAR won, but only slightly, and I still went with XZ for the project) on the corpus of Super Nintendo chiptune sets. Next is the corpus of Nintendo DS chiptunes.

  Repacking Nintendo DS 2SF
  The prevailing chiptune format for storing Nintendo DS songs is the .2sf format. This is a subtype of the Portable Sound Format (PSF). The designers had the foresight to build compression directly into the format. Much of payload data in a PSF file is compressed with zlib. Since I already incorporated Embedded XZ into the player project, I decided to try repacking the PSF payload data from zlib -> xz.

  In an effort to not corrupt standards too much, I changed the ’PSF’ file signature (seen in the first 3 bytes of a file) to ’psf’.

  Results
  There are about 900 Nintendo DS games currently represented in my website’s archive. Total size of the original PSF archive, payloads packed with zlib : 2.992 GB. Total size of the same archive with payloads packed as xz : 2.059 GB.

  Using xz vs. zlib saved me nearly a gigabyte of storage. That extra storage doesn’t really impact my hosting plan very much (I have 1/2 TB, which is why I’m so nonchalant about hosting the massive MPlayer Samples Archive). However, smaller individual files translates to a better user experience since the files are faster to download.

  Here is a pretty picture to illustrate the space savings :

  
  
  

  The blue occasionally appears to dip below the orange but the data indicates that xz is always more efficient than zlib. Here’s the raw data (comes in vanilla CSV flavor too).

  Interface Impact
  So the good news for the end user is that the songs are faster to load up front. The downside is that there can be a noticeable delay when changing tracks. Even though all songs are packaged into one file for download, and the entire file is downloaded before playback begins, each song is individually compressed. Thus, changing tracks triggers another decompression operation. I’m toying the possibility of some sort of background process that decompresses song (n+1) while playing song (n) in order to help compensate for this.

  I don’t like the idea of decompressing everything up front because A) it would take even longer to start playing ; and B) it would take a huge amount of memory.

  Corner Case
  There was at least one case in which I found zlib to be better than xz. It looks like zlib’s minimum block size is smaller than xz’s. I think I discovered xz to be unable to compress a few bytes to a block any smaller than about 60-64 bytes while zlib got it down into the teens. However, in those cases, it was more efficient to just leave the data uncompressed anyway.