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• Giving Thanks For VP8

  25 novembre 2010, par Multimedia Mike — VP8

  It’s the Thanksgiving holiday here in the United States. I guess that’s as good a reason as any to release a first cut of my VP8 encoder. In order to remind people that they shouldn’t expect phenomenal quality from it — and to discourage inexperienced people from trying to create useful videos with it — I have hardcoded the quantizers to their maximum settings. For those not skilled in the art, this is the setting that yields maximum compression and worst quality. When compressing the Big Buck Bunny logo image, the resulting file is only 2839 bytes but observe the reconstructed quality :

  
  
  It really just looks like a particularly stormy day in the forest.
  

  First VP8 File From An Independent Encoder
  I found a happy medium on the quantizer scale and encoded the first 30 seconds of Big Buck Bunny for your inspection. I guess this makes it the first VP8/WebM file from an independent encoder (using FFmpeg’s Matroska muxer as well).

  Download : bbb-360p-30sec-q40.webm ( 13 MBytes)

  I think the quality makes it look like it was digitized from an old VHS tape.

  For fun, here’s the version with the quantizer cranked to the max : bbb-360p-30sec-q127.webm ( 1.3 MBytes)

  Aside : I was going to encapsulate the video in this post using a bare HTML5 <video> tag for the benefit of the small browsing population who could view that (indeed, it works fine in Chrome). But that would be insane due to the fact that supporting browsers preload the video with no easy (read : without the help of JavaScript) method for overriding this unacceptable default.

  The Code
  I’m still trying to get over my fear of git. To that end, I have posted the code on Github :

  https://github.com/multimediamike/ffvp8enc

  I still don’t like you, git. But I’m sure we’ll find some way to make this work.

  Other required code changes in the basic FFmpeg tree :

  • Of course, copy vp8enc.c into libavcodec/
  • In libavcodec/allcodecs.c, ’REGISTER_DECODER (VP8, vp8);’ turns into ’REGISTER_ENCDEC (VP8, vp8);’
  • Add ’OBJS-$(CONFIG_VP8_ENCODER) += vp8enc.o’ to libavcodec/Makefile

  Further Work
  About the limitations and work yet to do :

  • it’s still intra-only, no interframes (which is where a lot of compression occurs)
  • no rate control or distortion optimization, obviously
  • no intra 4x4 coding (that’s close to working but didn’t my little T-day deadline)
  • no quantization control ; this should really be hooked up to the FFmpeg command line but I’m not sure how
  • encoder writes into a static-sized, 1/2 MB memory buffer ; this can overflow
  • code is a mess (what did you expect at this stage of the game ?)
  • lots and lots of other things, surely

• Winamp and the March of GUI

  1er juillet 2012, par Multimedia Mike — General, ars technica, gui, user interface, winamp

  Ars Technica recently published a 15-year retrospective on the venerable Winamp multimedia player, prompting bouts of nostalgia and revelations of "Huh ? That program is still around ?" from many readers. I was among them.

  
  
  

  I remember first using Winamp in 1997. I remember finding a few of these new files called MP3s online and being able to play the first 20 seconds using the official Fraunhofer Windows player— full playback required the fully licensed version. Then I searched for another player and came up with Winamp. The first version I ever used was v1.05 in the summer of 1997. I remember checking the website often for updates and trying out every single one. I can’t imagine doing that nowadays— programs need to auto-update themselves (which Winamp probably does now ; I can’t recall the last time I used the program).

  Video Underdog
  The last time Winamp came up on my radar was early in 2003 when a new version came with support for a custom, proprietary multimedia audio/video format called Nullsoft Video (NSV). I remember the timeframe because the date is indicated in the earliest revision of my NSV spec document (back when I was maintaining such docs in a series of plaintext files). This was cobbled together from details I and others in the open source multimedia community sorted out from sample files. It was missing quite a few details, though.

  Then, Winamp founder Justin Frankel — introduced through a colleague on the xine team — emailed me his official NSV format and told me I was free to incorporate details into my document just as long as it wasn’t obvious that I had the official spec. This put me in an obnoxious position of trying to incorporate details which would have been very difficult to reverse engineer without the official doc. I think I coped with the situation by never really getting around to updating my doc in any meaningful way. Then, one day, the official spec was released to the world anyway, and it is now mirrored here at multimedia.cx.

  I don’t think the format ever really caught on in any meaningful way, so not a big deal. (Anytime I say that about a format, I always learn it saw huge adoption is some small but vocal community.)

  What’s Wrong With This Picture ?
  What I really wanted to discuss in this post was the matter of graphical user interfaces and how they have changed in the last 15 years.
  
  I still remember when I first downloaded Winamp v1.05 and tried it on my Windows machine at the time. Indignantly, the first thought I had was, "What makes this program think it’s so special that it’s allowed to violate the user interface conventions put forth by the rest of the desktop ?" All of the Windows programs followed a standard set of user interface patterns and had a consistent look and feel... and then Winamp came along and felt it could violate all those conventions.

  I guess I let the program get away with it because it was either that or only play 20-second clips from the unregistered Fraunhofer player. Though incredibly sterile by comparison, the Fraunhofer player, it should be noted, followed Windows UI guidelines to the letter.

  As the summer of 1997 progressed and more Winamp versions were released, eventually one came out (I think it was v1.6 or so) that supported skins. I was excited because there was a skin that made the program look like a proper Windows program— at least if you used the default Windows color scheme, and had all of your fonts a certain type and size.

  Skins were implemented by packaging together a set of BMP images to overlay on various UI elements. I immediately saw a number of shortcomings with this skinning approach. A big one was UI lock-in. Ironically, if you skin an app and wish to maintain backwards compatibility with the thousands of skins selflessly authored by your vibrant community (seriously, I couldn’t believe how prolific these things were), then you were effectively locked into the primary UI. Forget about adding a new button anywhere.

  Another big problem was resolution-independence. Basing your UI on static bitmaps doesn’t scale well with various resolutions. Winamp had its normal mode and it also had double-sized mode.

  Skins proliferated among many types of programs in the late 1990s. I always treasured this Suck.com (remember them ? that’s a whole other nostalgia trip) essay from April, 2000 entitled Skin Cancer. Still, Winamp was basically the standard, and the best, and I put away my righteous nerd rage and even dug through the vast troves of skins. I remember settling on Swankamp for a good part of 1998, probably due to the neo-swing revival at the time.

  
  
  

  Then again, if Winamp irked me, imagine my reaction when I was first exposed to the Sonique Music Player in 1998 :

  
  
  

  The New UI Order
  Upon reflection, I realize now that I had a really myopic view of what a computer GUI should be. I thought the GUIs were necessarily supposed to follow the WIMP (windows, icons, mouse, pointer) paradigm and couldn’t conceive of anything different. For a long time, I couldn’t envision a useful GUI on a small device (like a phone) because WIMP didn’t fit well on such a small interface (even though I saw various ill-fated attempts to make it work). This thinking seriously crippled me when I was trying to craft a GUI for a custom console media player I was developing as a hobby many years ago.

  I’m looking around at what I have open on my Windows 7 desktop right now. Google Chrome browser, Apple iTunes, Adobe Photoshop Elements, and VMware Player are 4 programs which all seem to have their own skins. Maybe Winamp doesn’t look so out of place these days.

• ffmpeg export multichannel audio -map

  8 avril 2014, par speedyrazor

  I am trying to export all audio channels from a multichannel quicktime file with ffmpeg which has the following audio configuration, but am unsure if the command below is correct. All the files look and play correct in Quicktime player except the L+R_Total.wav which refuses to play in Quicktime player but plays fine in VLC, so not sure if i'm using the wrong command :

  Track 1 - mono
  
  Track 2 - mono
  
  Track 3 - mono
  
  Track 4 - mono
  
  Track 5 - mono
  
  Track 6 - mono
  
  Track 7 - stereo

  I am using :

  /Users/me/Desktop/python/ffmpeg/ffmpeg -i /Users/me/Desktop/test.mov -acodec pcm_s24le -map 0:1 -y Left.wav -acodec pcm_s24le -map 0:2 Right.wav -acodec pcm_s24le -map 0:3 Center.wav -acodec pcm_s24le -map 0:4 LFE.wav -acodec pcm_s24le -map 0:5 Left_Surround.wav -acodec pcm_s24le -map 0:6 Right_Surround.wav -acodec pcm_s24le -map 0:7 Left+Right_Total.wav

  Here is the printout from the terminal :

      MacBook-Pro:~ me$ /Users/me/Desktop/python/ffmpeg/ffmpeg -i /Users/me/Desktop/test.mov -acodec pcm_s24le -map 0:1 -y Left.wav -acodec pcm_s24le -map 0:2 Right.wav -acodec pcm_s24le -map 0:3 Center.wav -acodec pcm_s24le -map 0:4 LFE.wav -acodec pcm_s24le -map 0:5 Left_Surround.wav -acodec pcm_s24le -map 0:6 Right_Surround.wav -acodec pcm_s24le -map 0:7 Left+Right_Total.wav
  
  ffmpeg version 2.2 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Mar 25 2014 15:00:55 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  
    configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --arch=x86_64 --enable-runtime-cpudetect
  
    libavutil      52. 66.100 / 52. 66.100
  
    libavcodec     55. 52.102 / 55. 52.102
  
    libavformat    55. 33.100 / 55. 33.100
  
    libavdevice    55. 10.100 / 55. 10.100
  
    libavfilter     4.  2.100 /  4.  2.100
  
    libswscale      2.  5.102 /  2.  5.102
  
    libswresample   0. 18.100 /  0. 18.100
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/me/Desktop/test.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      creation_time   : 2014-03-06 11:25:34
  
    Duration: 00:01:03.48, start: 0.000000, bitrate: 153967 kb/s
  
      Stream #0:0(eng): Video: prores (apch / 0x68637061), yuv422p10le, 1920x1080, 144704 kb/s, SAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 23976 tbn, 23976 tbc (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
        timecode        : 00:00:00:00
  
      Stream #0:1(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 1 channels (FL), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:2(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 1 channels (FR), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:3(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:4(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 1 channels (LFE), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:5(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 1 channels (BL), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:6(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 1 channels (BR), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:7(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, downmix, s32, 2304 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:8(eng): Data: none (tmcd / 0x64636D74) (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:26:04
  
        handler_name    : Apple Alias Data Handler
  
        timecode        : 00:00:00:00
  
  Output #0, wav, to 'Left.wav':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      ISFT            : Lavf55.33.100
  
      Stream #0:0(eng): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels (FL), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
  Output #1, wav, to 'Right.wav':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      ISFT            : Lavf55.33.100
  
      Stream #1:0(eng): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels (FR), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
  Output #2, wav, to 'Center.wav':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      ISFT            : Lavf55.33.100
  
      Stream #2:0(eng): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, mono, s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
  Output #3, wav, to 'LFE.wav':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      ISFT            : Lavf55.33.100
  
      Stream #3:0(eng): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels (LFE), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
  Output #4, wav, to 'Left_Surround.wav':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      ISFT            : Lavf55.33.100
  
      Stream #4:0(eng): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels (BL), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
  Output #5, wav, to 'Right_Surround.wav':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      ISFT            : Lavf55.33.100
  
      Stream #5:0(eng): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels (BR), s32, 1152 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
  Output #6, wav, to 'Left+Right_Total.wav':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      ISFT            : Lavf55.33.100
  
      Stream #6:0(eng): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, downmix, s32, 2304 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-03-06 11:25:34
  
        handler_name    : Apple Alias Data Handler
  
  Stream mapping:
  
    Stream #0:1 -> #0:0 (pcm_s24le -> pcm_s24le)
  
    Stream #0:2 -> #1:0 (pcm_s24le -> pcm_s24le)
  
    Stream #0:3 -> #2:0 (pcm_s24le -> pcm_s24le)
  
    Stream #0:4 -> #3:0 (pcm_s24le -> pcm_s24le)
  
    Stream #0:5 -> #4:0 (pcm_s24le -> pcm_s24le)
  
    Stream #0:6 -> #5:0 (pcm_s24le -> pcm_s24le)
  
    Stream #0:7 -> #6:0 (pcm_s24le -> pcm_s24le)
  
  Press [q] to stop, [?] for help
  
  size=    8927kB time=00:01:03.48 bitrate=1152.0kbits/s    
  
  video:0kB audio:71415kB subtitle:0 data:0 global headers:0kB muxing overhead -87.499863%