Recherche avancée

Sur d’autres sites (5338)

• avformat/mov : compute absolute dts difference without overflow in mov_find_next_sample()

  30 septembre 2023, par Michael Niedermayer

  avformat/mov : compute absolute dts difference without overflow in mov_find_next_sample()
  Fixes : signed integer overflow : -9223372036854775808 - 9222726413022000000 cannot be represented in type 'long'
  
  Fixes : 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_MOV_fuzzer-5959420033761280
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mov.c

• Difference between duration from mvhd box and ffprobe for mp4 file

  11 juillet 2023, par Jiyeon Park

  I need to determine the duration of the video without relying on ffmpeg/ffprobe. To accomplish this, I created a program that searches for the mvhd box, reads its timescale and duration, and calculates the duration in seconds by dividing the duration by the timescale.

  


  To validate my approach, I compared the calculated duration with the result obtained from ffprobe. However, there was a slight discrepancy. For instance, the calculated duration was 26.031 seconds (26031/1000), whereas ffprobe reported it as 25.98 seconds.

  


  I'm curious about the reason behind this inconsistency. Is it possible that the video metadata stored in the mvhd box differs from the actual length of the video ?

  


• Not able to merge init.mp4 and seg-*.m4s with ffmpeg and python due to its file format difference

  1er février 2023, par XiBBaL

  I'm developing video downloader (only for free videos) for korean anime streaming site https://laftel.net/

  


  I guess laftel.net uses mpeg-dash for their streaming.
I found "init.mp4" file and "segments-number.m4s" files in chrome developer tools.

  


  Code below downloads seg-1.m4s (name of the first segment) to seg-239.m4s (name of the last segment) file and init.mp4 file and it works.

  


  
(Skip the beginning becasue there is a code that collects "Request-URL" for each .m4s files in network stream)


#variable "found" is part of the "Request-URL"

def curl_m4s():
    for i in range(1,240): #number of the .m4s segment file is constant at 239
        vid_url = f"https://mediacloud.laftel.net/{found}/video/avc1/2/seg-{i}.m4s"
        aud_url = f"https://mediacloud.laftel.net/{found}/audio/mp4a/eng/seg-{i}.m4s"
        
        if i < 10: #for single digit num
            os.system(f"curl {vid_url} > {location}/vids/vid00{i}.m4s")
            os.system(f"curl {aud_url} > {location}/auds/aud00{i}.m4s")
            sleep(random.randint(1,3))
            
        elif i < 100: #for double digit num
            os.system(f"curl {vid_url} > {location}/vids/vid0{i}.m4s")
            os.system(f"curl {aud_url} > {location}/auds/aud0{i}.m4s")
            sleep(random.randint(1,3))
            
        else: #for three digit num
            os.system(f"curl {vid_url} > {location}/vids/vid{i}.m4s")
            os.system(f"curl {aud_url} > {location}/auds/aud{i}.m4s")
            sleep(random.randint(1,3))

location = os.getcwd()

os.system(f"curl https://mediacloud.laftel.net/{found}/video/avc1/2/init.mp4 > {location}/vids/vid_init.mp4")
os.system(f"curl https://mediacloud.laftel.net/{found}/audio/mp4a/eng/init.mp4 > {location}/auds/aud_init.mp4")
os.system(f"curl https://mediacloud.laftel.net/{found}/stream.mpd > {location}/stream.mpd")

curl_m4s()
#use curl in cmd and downloads each of the .m4s (001 ~ 239)

    


  


  So in the vids folder i have "init.mp4" for video and "seg-1.m4s seg-239.m4s" for video
and in the auds folder i have "init.mp4" for audio and "seg-1.m4s seg-239.m4s" for audio

  


  Problem is, I cannot merge init file and segment files.
I have no idea about combining .mp4 and .m4s together.
There are a lot of example codes for merging init.m4s + seg-.m4s but I couldn't find init.mp4 + seg-.mp4 codes.

  


  I tried to merge segments together first, like this and it works.

  


  location = os.getcwd()

os.system(f"cd {location}")
os.system("copy /b vid*.m4s vid_full.m4s")


  


  and now, i want to merge init.mp4 becasue it has very much information about whole video files.
But how ??

  


  I tried these and none of them worked (looks like Successfull merge but it do not contain any watchable video)

  


  # vid_full is merged segment files (seg-1.m4s + ... + seg-239.m4s)
 
1. 
os.system("copy /b init.mp4 + vid*.m4s video_full.m4s")
os.system("ffmpeg -i video_full.m4s -c:a copy video_full.mp4")


2. 
os.system("type vid_init.mp4 index.txt > Filename.mp4")


3. 
import os 

os.system("ffmpeg -i vid_full.m4s -c:a copy vid_full.mp4")
os.system("copy /b vid_init.mp4 + vid_full.mp4 VIDEO.mp4")


  


  All problem occurs the format of the init file is .mp4. If it was .m4s I guess I could merge it.

  


  and I guess i must merge init file and segments files together both in .m4s format. Is it right ?
Via ffmpeg, i couldn't encode init.mp4 to init.m4s so this is the problme also.

  


  So, Please help me merge init.mp4 and segments.m4s

  


  All methods are wellcome at least it is based on python.

  


  

  1. I tried to merge init.mp4 + merged_segment.m4s but it failed

  


  2. I tried to convert init.mp4 to init.m4s via ffmpeg but it failed

  


  3. I tried to convert all the segments to .mp4 files and merge into init.mp4 but it failed

  


  


  I want to merge init file and segment files and make playable video.
Pleas Teach me how to do this.

  


  Links below are what I used for my test :

  


  [Laftel.net URL]
https://laftel.net/player/40269/46123

  


  [Request URL for init.mp4 (video)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/video/avc1/2/init.mp4

  


  [Request URL for init.mp4 (audio)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/audio/mp4a/eng/init.mp4

  


  [Request URL for seg-1.m4s (video)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/video/avc1/2/seg-1.m4s

  


  [Request URL for seg-1.m4s (audio)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/audio/mp4a/eng/seg-1.m4s