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• Revisiting the Belco Alpha-400

  26 août 2010, par Multimedia Mike — General

  Relieved of the primary FATE maintenance duties, I decided to dust off my MIPS-based Belco Alpha-400 and try to get it doing FATE cycles. And just as I was about to get FATE running, I saw that Mans already got his MIPS-based Popcorn Hour device to run FATE. But here are my notes anyway.

  
  
  

  Getting A Prompt
  For my own benefit, I made a PDF to remind me precisely how to get a root prompt on the Alpha-400. The ‘jailbreak’ expression seems a little juvenile to me, but it seems to be in vogue right now.

  alpha-400-jailbreak.pdf

  Toolchain
  When I last tinkered with the Alpha-400, I was trying to build a toolchain that could build binaries to run on the unit’s MIPS chip, to no avail. Sometime last year, MichaelK put together x86_32-hosted toolchains that are able to build mipsel 32-bit binaries for Linux 2.4 and 2.6. The Alpha-400 uses a 2.4 kernel and the corresponding toolchain works famously for building current FFmpeg (--disable-devices is necessary for building).

  FATE Samples
  Next problem : Making the FATE suite available to the Alpha-400. I copied all of the FATE suite samples onto a VFAT-formatted SD card. The filename case is not preserved for all files which confounds me since it is preserved in other cases. I tried formatting the card for ext3 but the Alpha-400 would not mount it, even though /proc/filesystems lists ext3 (supporting an older version of ext3 ?).

  Alternative : Copy all of the FATE samples to the device’s rootfs. Space will be a little tight, though. Then again, there is over 600 MB of space free ; I misread earlier and thought there were only 300 MB free.

  Remote Execution
  To perform FATE cycles on a remote device, it helps to be able to SSH into that remote device. I don’t even want to know how complicated it would be to build OpenSSH for the device. However, the last time I brought up this topic, I learned about a lighter weight SSH replacement called Dropbear. It turns out that Dropbear runs great on this MIPS computer.

  Running FATE Remotely
  I thought all the pieces would be in place to run FATE at this point. However, there is one more issue : Running FATE on a remote system requires that the host and the target are sharing a filesystem somehow. My personal favorite remote filesystem method is sshfs which is supposed to work wherever there is an SSH server. That’s not entirely true, though– sshfs also requires sftp-server to be installed on the server side, a program that Dropbear does not currently provide.

  I’m not even going to think about getting Samba or NFS server software installed on the Alpha-400. According to the unit’s /proc/filesystems file, nfs is a supported filesystem. I hate setting up NFS but may see if I can get that working anyway.

  Residual Weirdness
  The unit comes with the venerable Busybox program (BusyBox v1.4.1 (2007-06-01 20:37:18 CST) multi-call binary) for most of its standard command line utilities. I noticed a quirk where BusyBox’s md5sum gives weird hex characters. This might be a known/fixed issue.

  Another item is that the Alpha-400′s /dev/null file only has rwxr-xr-x per default. This caused trouble when I first tried to scp using Dropbear using a newly-created, unprivileged user.

• How to reduce file size of a video without loosing quality using an ffmpeg command ? [closed]

  11 mars 2024, par Shadab Mehdi

  I have received a video that is Full HD 1920 x 1080 and is nearly 62 GB. I know something is off here. I have seen similar videos under 3-4 GB.

  


  I tried to reduce the size by running the following command

  


  ffmpeg -i MyVideo.mpg -vcodec libx265 -crf 28 Compressed.mp4


  


  But it produced horrible out-of-sync audio. The video quality was OK.

  


  Here is a dump of ffprobe video output for better understanding.

  


  ffprobe -v quiet -print_format json -show_format -show_streams -print_format json MyVideo.mpg


  


  The output of the above command produces this response

  


  {
  "streams": [
    {
      "index": 0,
      "codec_name": "mpeg2video",
      "codec_long_name": "MPEG-2 video",
      "profile": "Main",
      "codec_type": "video",
      "codec_tag_string": "[0][0][0][0]",
      "codec_tag": "0x0000",
      "width": 1920,
      "height": 1080,
      "coded_width": 0,
      "coded_height": 0,
      "closed_captions": 0,
      "film_grain": 0,
      "has_b_frames": 1,
      "sample_aspect_ratio": "1:1",
      "display_aspect_ratio": "16:9",
      "pix_fmt": "yuv420p",
      "level": 4,
      "color_range": "tv",
      "chroma_location": "left",
      "field_order": "progressive",
      "refs": 1,
      "id": "0x1e0",
      "r_frame_rate": "25/1",
      "avg_frame_rate": "25/1",
      "time_base": "1/90000",
      "start_pts": 22503,
      "start_time": "0.250033",
      "duration_ts": 643863600,
      "duration": "7154.040000",
      "extradata_size": 150,
      "disposition": {
        "default": 0,
        "dub": 0,
        "original": 0,
        "comment": 0,
        "lyrics": 0,
        "karaoke": 0,
        "forced": 0,
        "hearing_impaired": 0,
        "visual_impaired": 0,
        "clean_effects": 0,
        "attached_pic": 0,
        "timed_thumbnails": 0,
        "non_diegetic": 0,
        "captions": 0,
        "descriptions": 0,
        "metadata": 0,
        "dependent": 0,
        "still_image": 0
      },
      "side_data_list": [
        {
          "side_data_type": "CPB properties",
          "max_bitrate": 80000000,
          "min_bitrate": 0,
          "avg_bitrate": 0,
          "buffer_size": 9781248,
          "vbv_delay": -1
        }
      ]
    },
    {
      "index": 1,
      "codec_name": "mp2",
      "codec_long_name": "MP2 (MPEG audio layer 2)",
      "codec_type": "audio",
      "codec_tag_string": "[0][0][0][0]",
      "codec_tag": "0x0000",
      "sample_fmt": "s16p",
      "sample_rate": "48000",
      "channels": 2,
      "channel_layout": "stereo",
      "bits_per_sample": 0,
      "initial_padding": 0,
      "id": "0x1c0",
      "r_frame_rate": "0/0",
      "avg_frame_rate": "0/0",
      "time_base": "1/90000",
      "start_pts": 15303,
      "start_time": "0.170033",
      "duration_ts": 643870080,
      "duration": "7154.112000",
      "bit_rate": "384000",
      "disposition": {
        "default": 0,
        "dub": 0,
        "original": 0,
        "comment": 0,
        "lyrics": 0,
        "karaoke": 0,
        "forced": 0,
        "hearing_impaired": 0,
        "visual_impaired": 0,
        "clean_effects": 0,
        "attached_pic": 0,
        "timed_thumbnails": 0,
        "non_diegetic": 0,
        "captions": 0,
        "descriptions": 0,
        "metadata": 0,
        "dependent": 0,
        "still_image": 0
      }
    }
  ],
  "format": {
    "filename": "MyVideo.mpg",
    "nb_streams": 2,
    "nb_programs": 0,
    "format_name": "mpeg",
    "format_long_name": "MPEG-PS (MPEG-2 Program Stream)",
    "start_time": "0.170033",
    "duration": "7154.120000",
    "size": "62752258052",
    "bit_rate": "70171881",
    "probe_score": 26
  }
}


  


• ffmpeg taking too much time to compress videos in a nest Js project [closed]

  30 août 2023, par Sheeraz

  I am trying to read a video as a stream from firebase and compress it using ffmpeg an it is too much time for the job to complete such that my call breaks before its done and I am getting socket hangup error. I have tried to increase the timeout of the call to 540s but it is still not enought for the job to be done. The framework I am using is nestJs with react as front-end. This is a web-app and the feature I am working on is a video recording functionality.

  


  Here is the code I am trying to run. The library I am using is "fluent-ffmpeg" : "^2.1.2", and
"ffmpeg" : "^0.0.4",

  


  const bucket = storage.bucket('my-bucket.appspot.com');
      const filePath = 'videos/video.mp4'; // Replace with the full path to your file
      const videoFile = bucket.file(filePath);
      const readStream = videoFile.createReadStream();
const ffmpegCommand = ffmpeg();
      ffmpegCommand.input(readStream);
      ffmpegCommand
        .outputOptions([
          '-preset ultrafast',
          '-c:v libx264',
          '-c:a aac',
          '-vf scale=640:480',
        ])
        .format('wav');
const outputStream = await ffmpegCommand.pipe();