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• speedhq : fix behavior of single-field decoding

  3 août 2017, par Steinar H. Gunderson

  speedhq : fix behavior of single-field decoding
  The height convention for decoding frames with only a single field made sense
  
  for compatibility with legacy decoders, but doesn't really match the convention
  
  used by NDI, which is the primary (only ?) user. Thus, change it to simply
  
  assuming that if the two fields overlap, the frame is meant to be a single
  
  field and the frame height matches the field height.
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/speedhq.c

• How do I remux/transcode a progressive file in ffmpeg ?

  3 décembre 2014, par Levi Roberts

  Here’s what I’m trying to do.

  My primary objective is to remux or transcode a currently downloading media file for AppleTV and iOS compatible streaming.

  I am doing this by looking at the media file and only transcoding when necessary, otherwise it will only alter the container the video/audio lives in. This will reduce overhead for files that are already compatible. The specific compatible output I am looking for is AppleTV3 and iOS.

  I have a file that is progressive, meaning that it is downloading using another download manager or another app without the help of nodejs. This file may or may not have the moov information available in the beginning of the file. It just so happens, that I believe my test file does.

  I have some code that is partially working and it would make sense to be able to get this code fully working. That said, I’m not dismissing alternative ways to do this.

  My primary problem (I think) has to do with the moov header location or that it’s being set incorrectly. I’m hoping the fix is as simple as correcting my poor ffmpeg knowledge with command line parameters.

  I am piping the file to and from ffmpeg via GrowingFile and fs.createWriteStream respectively.

  My code for doing so is :

  var fs = require('fs');
  
  var child = require('child_process');
  
  
  
  var GrowingFile = require('growing-file');
  
  var input_file = GrowingFile.open('./tmp/input.mp4');
  
  var output_file = fs.createWriteStream('./tmp/output.m4v');
  
  
  
  // I've tried various args and ffmpeg params here without success.
  
  var args = ['-re', '-i', 'pipe:0', '-g', '52', '-ab', '64k', '-vcodec', 'libx264', '-vb', '448k', '-f', 'mp4', '-movflags', 'frag_keyframe+faststart', 'pipe:1'];
  
  var trans_proc = child.spawn('ffmpeg', args, null); 
  
  
  
  input_file.pipe(trans_proc.stdin);
  
  trans_proc.stdout.pipe(output_file);

  I am also temporarily trying to make these files work as intended via ffmpeg command line alone, without success. That command is :

  ffmpeg -i original.mp4 -vcodec copy -r 24 output.m4v

  Snippet of original.mp4 via mediainfo :

  General
  
  Format                                   : MPEG-4
  
  Format profile                           : Base Media / Version 2
  
  Codec ID                                 : mp42
  
  File size                                : 9.87 MiB
  
  Duration                                 : 43mn 14s
  
  Overall bit rate mode                    : Variable
  
  Overall bit rate                         : 31.9 Kbp
  
  
  
  Video
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L2.1
  
  Codec ID                                 : avc1
  
  Duration                                 : 43mn 14s
  
  Width                                    : 480 pixels
  
  Height                                   : 268 pixels
  
  Color space                              : YUV
  
  Scan type                                : Progressive
  
  Stream size                              : 67.5 MiB
  
  
  
  Audio
  
  Format                                   : AAC
  
  Format/Info                              : Advanced Audio Codec
  
  Format profile                           : LC
  
  Codec ID                                 : 40
  
  Duration                                 : 43mn 14s
  
  Bit rate mode                            : Variable
  
  Bit rate                                 : 96.0 Kbps

  What’s happening is that output.m4v has an incorrect duration of only the part of the file that’s already downloaded. The video reaches the end or a refresh happens to make the duration longer. This process repeats until the original file is done downloading. What I want is to be able to emulate/clone the duration of the input file to the output file .

• How can I make windows "like" the mp4 files I create in Linux and sync with Rsync

  17 juillet 2019, par Geoff Fox

  I am a meteorologist on TV remotely from a studio I built. My control room uses a TriCaster, an amazing studio-in-a-box which runs on a Windows 7 variant. I make my weather maps myself on a Centos 7 machine — around 40,000/day.

  I don’t entirely understand the problem, but here’s a quote from someone helping me at NewTek (the TriCaster company)

  Rsync is built on a *nix based environment where all the file permissions and attributes are based on the Linux environment. There is no meaning for this in NTFS and Windows. The result is you get files that will most likely have the read-only flag set or no flag at all. Other attributes will be delivered as null. I’m sure from your own programming experience, programs don’t like null values and they generally have to be accounted for very specifically.

  And so the finely tuned TriCaster stumbles, meaning lost frames or other problems caused by my short weather animations.

  Here are some samples of the Rsync code I use

  rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/conus*.mp4 /mnt/tricaster/Clips/Import
rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/nebraska*.mp4 /mnt/tricaster/Clips/Import
rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/northernplains*.mp4 /mnt/tricaster/Clips/Import

  These are mp4 files. They are only used locally. I really don’t care what flags are checked and permissions filled as long as Windows 7 doesn’t care.

  At this point I always like to tell folks, though I do write some code my last computer class was in high school,’67-68 semester. Thanks in advance for your help.