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• ffmpeg - concatenate large set of video files - file names

  5 avril 2023, par bunnyisblack

  I'm trying to concatenate multiple video files. They all use the same codec and frame rate. Anyway concatenation isn't a problem. I've done it before.

  


  The problem is to automate it ?

  


  The answer here shows method 2 to be used in windows to concatenate files.
It's really easy :

  


  (echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4


  


  First, we make a list of video files (by manually tying them out). Second, we execute.

  


  The problem is that I have multiple video files located in a single directory. The video files are named similar to this :

  


  \450_01_videoName.mp4
\450_02_videoNameFoo.mp4
\450_04_videoNameMoo.mp4
\451_01_videoNameRoo.mp4
\451_02_videoNameHoo.mp4


  


  Now look at the above list and imagine that it's 200 lines big in a single folder. I'm trying to concatenate video 450 into 1, then video 451 into 1 file, etc.

  


  I'm trying to automate this process with a good thousand video files.

  


  I can do it semi manually. Use cmd to create a list of file and folder path. But then I would manually, file by file, have to copy and paste it to create that list.txt.

  


  Is there a way to automate this ? I've done this manually with 20 video files and it was painful (but better then using a stand alone software, as all the videos were done in a batch after all was set up).

  


  Cheers.

  


  I've done the process semi manually. It worked, but took more time that it needs to take.

  


  ------UPDATE

  


  This is how I tackled the problem. It was slow and painful.

  


  Firslty, I used cmd "dir /b > file.txt" to extract all the names of video files in that directory.

  


  Then I painfully wrote the BAT file manually (for videos up to 500) for each video I wanted to merge. I used a few notepad++ shortcuts, for example, replacing the number '45' with 'echo file 45', this ensured I didn't need to type 'echo file' manually for every line. Then I also copy-pasted manually for every line '>>list.txt'. I painfully had to write out the output file name 50 different times.

  


  h:
cd "h:\video directory"
echo file 450_01_video.mp4 > list.txt
echo file 450_02_videoMoo.mp4 >> list.txt
echo file 450_03_videoFoo.mp4 >> list.txt
echo file 450_04_videoLoo.mp4 >> list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy 450Video.mp4
echo file 451_01_video.mp4 > list.txt
echo file 451_02_videoMoo.mp4 >> list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy 451Video.mp4


  


  Now imagine a line for every single video file that I had to do manually.

  


  There has to be a simple for loop solution.

  


  ANSWER - SOLVED

  


  I've used Armali's solution.

  


  h:
cd "h:\video directory"

SETLOCAL ENABLEDELAYEDEXPANSION
set number=999
for %%f in (???_*.mp4) do (
    set name=%%f
    set before=!number!
    set number=!name:~0,3!
    if !number! gtr !before! call :concat
    echo file !name! >>list.txt
)

:concat
    ffmpeg -safe 0 -f concat -i list.txt -c copy %before%Video.mp4
    del list.txt


  


  The output video files were named 412Video.mp4. I used the dir /b file.txt command to extract the list of original files. I then copied them into excel, delimited them and used the tricks to extract the number, name, and remove duplicates etc. I then combined each record with output video as a ren command. E.g. ren 412video.mp4 412.name.location.mp4. I copied that into cmd for a fast rename.

  


• ffmpeg creating mpeg-dash chunk files too slowly resulting in 404 errors

  17 juillet 2021, par Danny

  I have a hardware encoder feeding FFmpeg to create a MPEG-DASH Low Latency stream. It works well for a while, but after letting FFmpeg run for a while and reloading the page there are many 404 errors.

  


  When that happens, the dash.js player tries to fetch the segment file on the "live edge" but the file has not been created yet by FFmpeg. For example, after running for 20-30 minutes and loading the web page player, debug code in the web server shows :

  


  2021-07-16 16:46:30.64 : GET REQUEST : /data/ott/chunk-stream0-00702.m4s
2021-07-16 16:46:30.67 : NOT FOUND. Latest files on filesystem:
    chunk-stream0-00699.m4s.tmp
    chunk-stream0-00698.m4s
    chunk-stream0-00697.m4s
    chunk-stream0-00696.m4s
    ...


  


  So you can see the browser requested chunk 702 but the latest on the server is (part of) 699. With 2 second chunks, that is 3-5 seconds of content not yet available.

  


  To analyze, I modified FFmpeg's dashenc.c to add a timestamp every time a file is opened which displays like :

  


  [dash @ 0x9b17c0] 21:48:52.935 1626443332.935  : dashenc_io_open() - opened /data/ott/chunk-stream0-00060.m4s.tmp


  


  And loaded the timestamps into Excel.

  


  Despite a segment duration of 2.000 seconds, the average time between file opens is 2.011 seconds. Over two hours this accumulated to a 45 second difference between the calculated live edge and the latest file on the server.

  


  The HW encoder is set to 25 fps and a GOP size of 5. I've confirmed both by analyzing the H.264 NALUs output by the HW encoder.

  


  My Question : Is this a bug in FFmpeg or can I avoid this problem by adjusting the settings of either the HW encoder and/or FFmpeg options ?

  


  REFERENCE

  


  FFmpeg: Version 4.4 
Centos 8 
Apache 2.4.37


  


  FFmpeg command line (pipe is fed by process reading HW encoder)

  


  ffmpeg -re -loglevel verbose -an -f h264 -i pipe:17 -c:v copy \
-f dash -dash_segment_type mp4 -b:v 1000000 -seg_duration 2.000000 \
-frag_type duration -frag_duration 0.200000 -target_latency 1 \
-window_size 10 -extra_window_size 5 -remove_at_exit 1 -streaming 1 \
-ldash 1 -use_template 1 -use_timeline 0 -write_prft 1 -avioflags direct \
-fflags +nobuffer+flush_packets -format_options movflags=+cmaf \
-utc_timing_url /web/be/time.php /data/ott/master.mpd


  


  Modified dash_io_open() from dashenc.c

  


  static int 
dashenc_io_open(AVFormatContext *s, AVIOContext **pb, char *filename, AVDictionary **options)
{
    DASHContext *c = s->priv_data;
    int http_base_proto = filename ? ff_is_http_proto(filename) : 0;
    int err = AVERROR_MUXER_NOT_FOUND;
    if (!*pb || !http_base_proto || !c->http_persistent)
    {
        err = s->io_open(s, pb, filename, AVIO_FLAG_WRITE, options);

        // My Debug
        {
            char buf[20], milli[60];
            struct timeb tp;

            ftime(&tp); // sec + ms
            struct tm *tmInfo = localtime(&tp.time);

            // 2020-05-15 21:15:12.123
            strftime(buf, sizeof(buf), "%H:%M:%S", tmInfo);
            snprintf(milli, 59, "%s.%03d %d.%03d ", buf, tp.millitm, tp.time, tp.millitm);

            av_log(s, AV_LOG_INFO, "%s : dashenc_io_open() - opened %s\n", milli, filename);
        }
    }
    return err;
}


  


• Pyinstaller exe works halfway on another computer

  5 novembre 2022, par At Bay

  I wrote a code which uses FFMPEG and os, subprocess, datetime, speechrecognition, and xlsxwriter libraries. Below a brief sketch of the code - it goes through a directory of wav files and creates a transcription for X seconds in length and saves it into an excel sheet.
import os
import subprocess
import datetime
import speech_recognition as sr
import xlsxwriter

  


  def ffmpeg():
   #create clip
   subprocess.run(["ffmpeg", "-ss", starti, "-t", lengthi, "-i", filepathO, filepathNEW1])

   #convert to mono
   subprocess.run(["ffmpeg", "-i", filepathNEW1, "-ac", "1", filepathNEW2])
   
   #compres to 44.1 kHZ
   subprocess.run(["ffmpeg", "-i", filepathNEW2, "-ar", "44100", filepathNEW3])

def transcription():
    with sr.AudioFile(os.path.abspath(clippath)) as source:
       audio = r.record(source)  # read the entire audio file
       transcriptstring = str(r.recognize_google(audio, language = 'en', show_all=True))
       worksheet.write(tcol, transcriptstring)


#call functions in this order
for filename in os.listdir(ufolder):
   if (filename.endswith(".wav")):
       ffmpeg() #cuts clips, compresses to mono and 44.1 khz
       transcription() 

workbook.close()



  


  When I try to run the exe created by pyinstaller, I get the following error :

  


  Enter directory of wav files: C:\Users\myname\Downloads\&#xA;Enter clip start (seconds): 0&#xA;Enter desired clip length (seconds): 5&#xA;Traceback (most recent call last):&#xA;  File "cliptranscript.py", line 134, in <module>&#xA;  File "cliptranscript.py", line 47, in ffmpeg&#xA;  File "subprocess.py", line 503, in run&#xA;  File "subprocess.py", line 971, in __init__&#xA;  File "subprocess.py", line 1440, in _execute_child&#xA;FileNotFoundError: [WinError 2] The system cannot find the file specified&#xA;[13304] Failed to execute script &#x27;cliptranscript&#x27; due to unhandled exception!&#xA;</module>

  


  Below is a partial view of the folder created by pyinstaller :