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• FFMpeg and WebM/VP8

  25 novembre 2011, par Anand Suresh

  I am trying to use ffmpeg and ffserver to stream VP8 video.

  I am using the following command to start FFMpeg :

  ffmpeg -v 9 -loglevel 99 -f x11grab -s 1440x900 -r2 -i :0.0 -f webm http://localhost:8090/feed1.ffm

  The above command abruptly terminates generating the following error :

  > FFmpeg version 0.6.2-4:0.6.2-1ubuntu1.1, Copyright (c) 2000-2010 the Libav developers
  
    built on Sep 16 2011 16:57:46 with gcc 4.5.2
  
    configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  
    WARNING: library configuration mismatch
  
    libavutil   configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libavcodec  configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libavformat configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libavdevice configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libavfilter configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libswscale  configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libpostproc configuration: --extra-version=4:0.6.2-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libavutil     50.15. 1 / 50.15. 1
  
    libavcodec    52.72. 2 / 52.72. 2
  
    libavformat   52.64. 2 / 52.64. 2
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libavfilter    1.19. 0 /  1.19. 0
  
    libswscale     0.11. 0 /  0.11. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  [x11grab @ 0x9869420]device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1440 height: 900
  
  [x11grab @ 0x9869420]shared memory extension  found
  
  [x11grab @ 0x9869420]Probe buffer size limit 5000000 reached
  
  [x11grab @ 0x9869420]Estimating duration from bitrate, this may be inaccurate
  
  Input #0, x11grab, from ':0.0':
  
    Duration: N/A, start: 1322253753.374957, bitrate: 41472 kb/s
  
      Stream #0.0, 1, 1/1000000: Video: rawvideo, bgra, 1440x900, 1/1, 41472 kb/s, 1 tbr, 1000k tbn, 1 tbc
  
  [libvpx @ 0x9876540]v0.9.6
  
  [libvpx @ 0x9876540]--enable-pic --enable-shared --disable-install-bins --disable-install-srcs --target=x86-linux-gcc
  
  [libvpx @ 0x9876540]vpx_codec_enc_cfg
  
  [libvpx @ 0x9876540]generic settings
  
    g_usage:                      0
  
    g_threads:                    0
  
    g_profile:                    0
  
    g_w:                          320
  
    g_h:                          240
  
    g_timebase:                   {1/30}
  
    g_error_resilient:            0
  
    g_pass:                       0
  
    g_lag_in_frames:              0
  
  [libvpx @ 0x9876540]rate control settings
  
    rc_dropframe_thresh:          0
  
    rc_resize_allowed:            0
  
    rc_resize_up_thresh:          60
  
    rc_resize_down_thresh:        30
  
    rc_end_usage:                 0
  
    rc_twopass_stats_in:          (nil)(0)
  
    rc_target_bitrate:            256
  
  [libvpx @ 0x9876540]quantizer settings
  
    rc_min_quantizer:             4
  
    rc_max_quantizer:             63
  
  [libvpx @ 0x9876540]bitrate tolerance
  
    rc_undershoot_pct:            95
  
    rc_overshoot_pct:             200
  
  [libvpx @ 0x9876540]decoder buffer model
  
    rc_buf_sz:                    6000
  
    rc_buf_initial_sz:            4000
  
    rc_buf_optimal_sz:            5000
  
  [libvpx @ 0x9876540]2 pass rate control settings
  
    rc_2pass_vbr_bias_pct:        50
  
    rc_2pass_vbr_minsection_pct:  0
  
    rc_2pass_vbr_maxsection_pct:  400
  
  [libvpx @ 0x9876540]keyframing settings
  
    kf_mode:                      1
  
    kf_min_dist:                  0
  
    kf_max_dist:                  9999
  
  [libvpx @ 0x9876540]
  
  [libvpx @ 0x9876540]vpx_codec_enc_cfg
  
  [libvpx @ 0x9876540]generic settings
  
    g_usage:                      0
  
    g_threads:                    1
  
    g_profile:                    0
  
    g_w:                          1440
  
    g_h:                          900
  
    g_timebase:                   {1/1}
  
    g_error_resilient:            0
  
    g_pass:                       0
  
    g_lag_in_frames:              0
  
  [libvpx @ 0x9876540]rate control settings
  
    rc_dropframe_thresh:          0
  
    rc_resize_allowed:            0
  
    rc_resize_up_thresh:          60
  
    rc_resize_down_thresh:        30
  
    rc_end_usage:                 0
  
    rc_twopass_stats_in:          (nil)(0)
  
    rc_target_bitrate:            200
  
  [libvpx @ 0x9876540]quantizer settings
  
    rc_min_quantizer:             1
  
    rc_max_quantizer:             38
  
  [libvpx @ 0x9876540]bitrate tolerance
  
    rc_undershoot_pct:            95
  
    rc_overshoot_pct:             200
  
  [libvpx @ 0x9876540]decoder buffer model
  
    rc_buf_sz:                    6000
  
    rc_buf_initial_sz:            4000
  
    rc_buf_optimal_sz:            5000
  
  [libvpx @ 0x9876540]2 pass rate control settings
  
    rc_2pass_vbr_bias_pct:        50
  
    rc_2pass_vbr_minsection_pct:  0
  
    rc_2pass_vbr_maxsection_pct:  400
  
  [libvpx @ 0x9876540]keyframing settings
  
    kf_mode:                      1
  
    kf_min_dist:                  0
  
    kf_max_dist:                  12
  
  [libvpx @ 0x9876540]
  
  [libvpx @ 0x9876540]vpx_codec_control
  
  [libvpx @ 0x9876540]  VP8E_SET_CPUUSED:             3
  
  [libvpx @ 0x9876540]  VP8E_SET_NOISE_SENSITIVITY:   0
  
  Output #0, webm, to 'http://127.0.0.1:8090/feed1.ffm':
  
    Metadata:
  
      encoder         : Lavf52.64.2
  
      Stream #0.0, 0, 1/1000: Video: libvpx, yuv420p, 1440x900, 1/1, q=2-31, 200 kb/s, 1k tbn, 1 tbc
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  [webm @ 0x98753b0]Writing block at offset 15, size 158658, pts 0, dts 0, duration 1000, flags 128
  
  [webm @ 0x98753b0]Starting new cluster at offset 158681 bytes, pts 0

  Can anyone point out what I am doing wrong here ? Why does ffmpeg die everytime it starts a new cluster ?

  Thanks

• Tele-Arena Lives On

  25 février 2011, par Multimedia Mike — Game Hacking

  Readers know I have a peculiar interest in taking apart video games and that I would rather study a game’s inner workings than actually play it. I take an interest on others’ efforts in this same area. It’s still in my backlog to take a closer look at Clone2727’s body of work. But I wanted to highlight my friend’s work on re-implementing a game called Tele-Arena.

  
  
  

  Back In The Day
  As some of you are likely aware, there was a dark age of online communication that predated the era of widespread internet access. This was known as "The BBS Age". People dialed into these BBSes using modems that operated at abysmal transfer speeds and would communicate with other users, upload and download files, and play an occasional game.

  BBS software evolved and perhaps the ultimate (and final) evolution was Galacticomm’s MajorBBS (MBBS). There were assorted games that plugged into the MBBS, all rendered in glorious color ANSI graphics. One of the most famous of these games was Tele-Arena (TA). TA was a multiplayer fantasy-themed text adventure game. Perhaps you could think of it as World of Warcraft, only rendered as interactive fiction instead of a rich 3D landscape. (Disclaimer : I might not be qualified to make that comparison since I have never experienced WoW firsthand, though I did play TA on and off about 17 years ago).

  TA was often compared to multi-user dungeons — or MUDs — that were played by telneting into internet servers hosting games. Such comparisons were usually unfavorable as people who had experience with both TA and MUDs were sniffy elitists with internet access who thought they were sooooo much better than those filthy, BBS-dialing serfs.

  Sorry, didn’t mean to open old wounds.

  Modern Retelling of A Classic Tale
  Anyway, my friend Ron Kinney is perhaps the world’s biggest fan of TA. So much so that he has re-implemented the engine in Java under the project name Ether. He’s in a similar situation as the ScummVM project in that, while the independent, open source engine is fair game for redistribution, it would be questionable to redistribute the original data files. That’s why he created an AreaBuilder application that generates independent game data files.

  Ironically, you can also telnet into a server on which Ron hosts an instance of Tele-Arena (ironic in the sense that the internet/BBS conflict gets a little blurry).

  I hope that one day Ron will regale us with the strangest tales from the classic TA days. My personal favorite was "Wrath of a Sysop."

• Notes on Linux for Dreamcast

  23 février 2011, par Multimedia Mike — Sega Dreamcast, VP8

  I wanted to write down some notes about compiling Linux on Dreamcast (which I have yet to follow through to success). But before I do, allow me to follow up on my last post where I got Google’s libvpx library decoding VP8 video on the DC. Remember when I said the graphics hardware could only process variations of RGB color formats ? I was mistaken. Reading over some old documentation, I noticed that the DC’s PowerVR hardware can also handle packed YUV textures (UYVY, specifically) :

  
  
  

  The video looks pretty sharp in the small photo. Up close, less so, due to the low resolution and high quantization of the test vector combined with the naive chroma upscaling. For the curious, the grey box surrounding the image highlights the 256-square texture that the video frame gets plotted on. Texture dimensions have to be powers of 2.

  Notes on Linux for Dreamcast
  I’ve occasionally dabbled with Linux on my Dreamcast. There’s an ancient (circa 2001) distro based around a build of kernel 2.4.5 out there. But I wanted to try to get something more current compiled. Thus far, I have figured out how to cross compile kernels pretty handily but have been unsuccessful in making them run.

  Here are notes are the compilation portion :
  

  • kernel.org provides a very useful set of cross compiling toolchains
  • get the gcc 4.5.1 cross toolchain for SH-4 (the gcc 4.3.3 one won’t work because the binutils is too old ; it will fail to assemble certain instructions as described in this post)
  • working off of Linux kernel 2.6.37, edit the top-level Makefile ; find the ARCH and CROSS_COMPILE variables and set appropriately :

    ARCH ?= sh
    CROSS_COMPILE ?= /path/to/gcc-4.5.1-nolibc/sh4-linux/bin/sh4-linux-
    

  • $ make dreamcast_defconfig
  • $ make menuconfig ... if any changes to the default configuration are desired
  • manually edit arch/sh/Makefile, changing :

    cflags-$(CONFIG_CPU_SH4) := $(call cc-option,-m4,) \
            $(call cc-option,-mno-implicit-fp,-m4-nofpu)
    

    to :

    cflags-$(CONFIG_CPU_SH4) := $(call cc-option,-m4,) \
            $(call cc-option,-mno-implicit-fp)
    

    I.e., remove the '-m4-nofpu' option. According to the gcc man page, this will "Generate code for the SH4 without a floating-point unit." Why this is a default is a mystery since the DC’s SH-4 has an FPU and compilation fails when enabling this option.

  • On that note, I was always under the impression that the DC sported an SH-4 CPU with the model number SH7750. According to this LinuxSH wiki page as well as the Linux kernel help, it actually has an SH7091 variant. This photo of the physical DC hardware corroborates the model number.
  • $ make ... to build a Linux kernel for the Sega Dreamcast

  Running
  So I can compile the kernel but running the kernel (the resulting vmlinux ELF file) gives me trouble. The default kernel ELF file reports an entry point of 0x8c002000. Attempting to upload this through the serial uploading facility I have available to me triggers a system reset almost immediately, probably because that’s the same place that the bootloader calls home. I have attempted to alter the starting address via ’make menuconfig’ -> System type -> Memory management options -> Physical memory start address. This allows the upload to complete but it still does not run. It’s worth noting that the 2.4.5 vmlinux file from the old distribution can be executed when uploaded through the serial loader, and it begins at 0x8c210000.