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• FFmpeg concat creating corrupted video part (Media Info provided)

  6 mai 2022, par krv

  I am using concat to join a list of video files with the following command

  


  ffmpeg -f concat -safe 0 -i filesList.txt -c copy output.mp4 


  


  The issue here is that there are a few files that were recorded in slow motion on my phone. The slow-motion files have the same frame rate as the other files.

  


  But when concatenated the part where the slow-motion files are concatenated appears to be frozen / glitch (it does not play a single frame).

  


  I am able to seek forward and backward the part that does not play. So the portion of the video that contained normal files plays and as soon as the slow-motion video comes, nothing plays, and when a normal file comes it starts playing again.

  


  I am attaching the media Info of both files

  


  Info of the slow motion file :

  


  General
Complete name :     I:\concate Test\VID20210727114100.mp4
Format :    MPEG-4
Format profile :    Base Media / Version 2
Codec ID :  mp42 (isom/mp42)
File size :     27.6 MiB
Duration :  1 min 0 s
Overall bit rate :  3 825 kb/s
Encoded date :  UTC 2021-07-27 06:11:08
Tagged date :   UTC 2021-07-27 06:11:08
xyz :   +21.6146+071.2342/
com.android.version :   11

Video
ID :    1
Format :    HEVC
Format/Info :   High Efficiency Video Coding
Format profile :    Main@L3.1@Main
Codec ID :  hvc1
Codec ID/Info :     High Efficiency Video Coding
Duration :  1 min 0 s
Source duration :   1 min 0 s
Bit rate :  3 771 kb/s
Width :     1 280 pixels
Height :    720 pixels
Display aspect ratio :  16:9
Frame rate mode :   Variable
Frame rate :    30.000 FPS
Minimum frame rate :    29.910 FPS
Maximum frame rate :    30.090 FPS
Real frame rate :   240.000 FPS
Color space :   YUV
Chroma subsampling :    4:2:0
Bit depth :     8 bits
Bits/(Pixel*Frame) :    0.136
Stream size :   27.2 MiB (99%)
Source stream size :    27.2 MiB (99%)
Title :     VideoHandle
Language :  English
Encoded date :  UTC 2021-07-27 06:11:08
Tagged date :   UTC 2021-07-27 06:11:08
Color range :   Limited
Color primaries :   BT.709
Transfer characteristics :  BT.709
Matrix coefficients :   BT.709
mdhd_Duration :     60524
Codec configuration box :   hvcC


  


  Info of the regular video file

  


  
General
Complete name :     I:\concate Test\VID20210727113901.mp4
Format :    MPEG-4
Format profile :    Base Media / Version 2
Codec ID :  mp42 (isom/mp42)
File size :     39.0 MiB
Duration :  37 s 930 ms
Overall bit rate :  8 615 kb/s
Encoded date :  UTC 2021-07-27 06:09:40
Tagged date :   UTC 2021-07-27 06:09:40
xyz :   +21.6146+071.2342/
com.android.version :   11

Video
ID :    1
Format :    HEVC
Format/Info :   High Efficiency Video Coding
Format profile :    Main@L4@Main
Codec ID :  hvc1
Codec ID/Info :     High Efficiency Video Coding
Duration :  37 s 930 ms
Source duration :   37 s 900 ms
Bit rate :  8 408 kb/s
Width :     1 920 pixels
Height :    1 080 pixels
Display aspect ratio :  16:9
Frame rate mode :   Variable
Frame rate :    29.604 FPS
Minimum frame rate :    29.508 FPS
Maximum frame rate :    29.605 FPS
Real frame rate :   30.000 FPS
Color space :   YUV
Chroma subsampling :    4:2:0
Bit depth :     8 bits
Bits/(Pixel*Frame) :    0.137
Stream size :   38.0 MiB (98%)
Source stream size :    38.0 MiB (98%)
Title :     VideoHandle
Language :  English
Encoded date :  UTC 2021-07-27 06:09:40
Tagged date :   UTC 2021-07-27 06:09:40
Color range :   Limited
Color primaries :   BT.709
Transfer characteristics :  BT.709
Matrix coefficients :   BT.709
mdhd_Duration :     37930
Codec configuration box :   hvcC

Audio
ID :    2
Format :    AAC LC
Format/Info :   Advanced Audio Codec Low Complexity
Codec ID :  mp4a-40-2
Duration :  37 s 909 ms
Bit rate mode :     Constant
Bit rate :  128 kb/s
Channel(s) :    2 channels
Channel layout :    L R
Sampling rate :     48.0 kHz
Frame rate :    46.875 FPS (1024 SPF)
Compression mode :  Lossy
Stream size :   592 KiB (1%)
Title :     SoundHandle
Language :  English
Encoded date :  UTC 2021-07-27 06:09:40
Tagged date :   UTC 2021-07-27 06:09:40




  


• ISO-9660 Compromise, Part 2 : Finding Root

  25 octobre 2021, par Multimedia Mike — General

  A long time ago, I dashed off a quick blog post with a curious finding after studying the ISO-9660 spec : The format stores multi-byte numbers in a format I termed “omni-endian”– the committee developing the format apparently couldn’t come to an agreement on this basic point regarding big- vs. little-endian encoding (I’m envisioning something along the lines of “tastes great ! … less filling !” in the committee meetings).

  I recently discovered another bit of compromise in the ISO-9660 spec : It seems that there are 2 different methods for processing the directory structure. That means it’s incumbent upon ISO-9660 creation software to fill in the data structures to support both methods, because some ISO-reading programs out there rely on one set of data structures while the rest prefer to read the other set.

  Background

  As a refresher, the “ISO” extension of an ISO file refers to the ISO-9660 specification. This is a type of read-only filesystem (i.e, the filesystem is created once and never updated after initial creation) for the purpose of storing on a read-only medium, often an optical disc (CD-ROM, DVD-ROM). The level of nostalgic interest I display for the ISO-9660 filesystem reminds me of my computer science curriculum professors from the mid-90s reminiscing about ye olden days of punchcard programming, but such is my lot. I’m probably also alone in my frustration of seeing rips of, e.g., GameCube or Xbox or 3DO games being tagged with the extension .ISO since those systems use different read-only filesystems.

  I recently fell in with an odd bunch called the eXoDOS project and was trying to help fill in a few gaps. One request was a 1994 game called Power Drive for DOS.

  
  
  

  
  

  My usual CD-ROM ripping method (for the data track) is a simple ‘dd’ command from a Linux command line to copy the string of raw sectors. However, it turned out to be unusually difficult to open the resulting ISO. A few of the the options I know of worked but most didn’t. What’s the difference ?

  Methods that work :

  • Mounting the file with the Linux iso9660 kernel module, i.e.,

    mount -t iso9660 /dev/optical-drive /mnt

    or

    mount -t iso9660 -o loop /path/to/Power-Drive.iso /mnt

  • Directory Opus
  • Windows 10 can read the filesystem when reading the physical disc
  • Windows 10 can burn the ISO image to a new CD (“right click” -> “Burn disc image”) ; this method does not modify any of the existing sectors but did append 149 additional empty sectors

  Methods that don’t work :

  • fuseiso
  • Dosbox
  • Winrar
  • 7zip
  • Daemon Tools
  • Imgburn
  • Internet Archive’s ISO lister (“View contents” on the ISO file)

  Understanding The Difference

  I think I might have a handle on why some tools are able to process this disc while most can’t. There appears to be 2 sets of data structures to describe the base of the filesystem : A root directory, and a path table. These both occur in the first substantive sector of the ISO-9660 filesystem, usually sector 16.

  A compact disc can be abstractly visualized as a long string of sectors, each one 2,352 bytes long. (See my Grand Unified Theory of Compact Disc post for deeper discussion.) A CD-ROM data track will contain 2048 bytes of data. Thus, sector 16 appears at 0x8000 of an ISO filesystem. I like the clarity of this description of the ISO-9660 spec. It shows that the path table is defined at byte 140 (little-endian ; big comes later) and location of the root directory is at byte 158. Thus, these locations generally occur at 0x808c and 0x809e.

  
  
  Primary Volume Descriptor
  

  The path table is highlighted in green and the root directory record is highlighted in red. These absolute locations are specified in sectors. So the path table is located at sector 0x12 = offset 0x9000 in the image, while the root directory record is supposed to be at sector 0x62 = 0x31000. Checking into those sectors, it turns out that the path table is valid while the root directory record is invalid. Thus, any tool that relies on the path table will be successful in interpreting the disc, while tools that attempt to recursively traverse starting from root directory record are gonna have a bad time.

  Since I was able to view the filesystem with a few different tools, I know what the root directory contains. Searching for those filenames reveals that the root directory was supposed to point to the next sector, number 0x63. So this was a bizarre off-by-1 error on the part of the ISO creation tool. Maybe. I manually corrected 0x62 -> 0x63 and that fixed the interaction with fuseiso, but not with other tools. So there may have been some other errors. Note that a quick spot-check of another, functional ISO revealed that this root directory sector is supposed to be exact, not 1-indexed.

  Upon further inspection, I noticed that, while fuseiso appeared to work with that one patch, none of the files returned correct data, and none of the directories contained anything. That’s when I noticed that ALL of the sector locations described in the various directory and file records are off by 1 !

  Further Investigation

  I have occasionally run across ISO images on the Internet Archive that return the error about not being able to read the contents when trying to “View contents” (error text : “failed to obtain file list from xyz.iso”, as seen with this ISO). Too bad I didn’t make a record of them because I would be interested to see if they have the same corruption.

  Eventually, I’ll probably be able to compile an archive of deviant ISO-9660 images. A few months ago, I was processing a large collection from IA and found a corrupted ISO which had a cycle, i.e., the subdirectory pointed to a parent directory, which caused various ISO tools to loop forever. Just one of those things that is “never supposed to happen”, so why write code to deal with it gracefully ?

  See Also

  • The disc archived at The Internet Archive
  • MobyGames Entry
  • Wikipedia Entry

  The post ISO-9660 Compromise, Part 2 : Finding Root first appeared on Breaking Eggs And Making Omelettes.

• How can I capture and record only specific part of the desktop using ffmpeg ?

  23 juillet 2018, par Benzi Avrumi

  This is how I’m using now to record the desktop.

  Using ffmpeg.exe : ffmpeg -f gdigrab -framerate 24 -i desktop -preset ultrafast -pix_fmt yuv420p out.mp4

  Or using csharp :

   using System;  
  
      using System.Collections.Generic;  
  
      using System.Linq;  
  
      using System.Text;  
  
      using System.Threading.Tasks;  
  
      using System.IO;  
  
      using System.Diagnostics;  
  
  
  
      namespace Ffmpeg_App  
  
      {  
  
          class Ffmpeg  
  
          {  
  
              Process process;  
  
  
  
              public void Start(string FileName, int Framerate)  
  
              {  
  
                  process = new System.Diagnostics.Process();  
  
                  process.StartInfo.FileName = @"D:\ffmpegx86\ffmpeg.exe"; // Change the directory where ffmpeg.exe is.  
  
                  process.EnableRaisingEvents = false;  
  
                  process.StartInfo.WorkingDirectory = @"D:\ffmpegx86"; // The output directory  
  
                  process.StartInfo.Arguments = @"-f gdigrab -framerate " + Framerate + " -i desktop -preset ultrafast -                                                                     pix_fmt yuv420p " + FileName;  
  
                  process.Start();  
  
                  process.StartInfo.UseShellExecute = false;  
  
                  process.StartInfo.CreateNoWindow = false;  
  
                  Close();  
  
              }  
  
  
  
              public void Close()  
  
              {  
  
                  process.Close();  
  
              }  
  
          }  
  
      }  

  And using it like this for example :

  Ffmpeg fpeg = new Ffmpeg(); 
  
  
  
  
  
      private void Start_Click(object sender, EventArgs e)  
  
              {  
  
                  fpeg.Start("test.mp4", 24);  
  
              }  
  
  
  
  
  
      private void Stop_Click(object sender, EventArgs e)  
  
              {  
  
                  fpeg.Close();  
  
              } 

  This will record the entire desktop window to a video file.
  But how can I record a specific rectangle area in the desktop ? For example to record only the right bottom corner rectangle size 10x10.

  So when I will play the video file I will see full screen video but only of the right bottom corner of the desktop.