Recherche avancée

Sur d’autres sites (8879)

• Incorrect values for song length (duration) in Mp3tag after ffmpeg FLAC to MP3 conversion

  29 mars 2024, par Clueless

  The problem

  


  As per this post, I use the following command to convert a flac file to mp3 while keeping all metadata :

  


  ffmpeg -i input.flac -ab 320k -map_metadata 0 -id3v2_version 3 output.mp3


  


  When inspecting the converted mp3 file by right-clicking it, going to properties and then details, everything looks in order. The value for "Length" is correct.

  


  

  


  When inspecting the converted mp3 file with Mp3tag, the value for "Length" is different. From my testing, the "Length" value is consistently about 28% of what it is supposed to be.

  


  

  


  Normally, this isn't an issue. Most music players I use, read the correct length value, same as Windows. However, I've recently discovered that Spotify Mobile for some reason ignores the length value that can be seen in the Windows panel and uses the one that can be seen in Mp3tag.

  


  I want to figure out what command I should use so that after the flac file has been converted to mp3, Mp3tag shows the correct length, and there by, Spotify Mobile reads the correct length as well.

  


  What I have tried

  


  1.
After converting the file to Mp3, I've tried reencoding the mp3 file into a... mp3 file using the following command :

  


  ffmpeg -i original.mp3 -c:v copy -c:a mp3 -vn -ar 44100 -ac 2 -b:a 320k copy.mp3


  


  

  


  As can be seen in the image above, this fixes the issue and the length is showing correctly in Mp3tag and in Spotify Mobile.

  


  Issues with this : Reencoding reduces quality and I don't know how to combine the previous flac conversion command and this one into one line.

  


  2.
I tried https://cloudconvert.com/flac-to-mp3 and it worked. The length is displayed correctly in Mp3tag. (What commands did they use on the server ???)

  


  

  


  Issues with this : I don't want to rely on a cloud service for conversion, I have a lot of files to convert and I'd prefer it to be done locally.

  


  Some demo files

  


  Here is a folder with a flac file, a bad mp3 file (wrong length) and a good mp3 file. It looks like if you preview the music in google drive, it also plays the wrong length for the bad mp3 (39s not 2m19s), while vlc, groove player, spotify (desktop not mobile) all play the correct full length (2m19s) for the bad mp3 file.

  


  Folder : here's the link

  


• How to convert AAC/MP4A to MP3 using FFMPEG in full length ? Audio file gets cut off after 1 second

  6 novembre 2022, par Avatar

  I have recorded an audio file with MediaRecorder on iPhone.

  


  As ffmpeg command I am using :

  


  ffmpeg -i 18380889311644327118 -ar 44100 -ac 2 -b:a 128k -c:a libmp3lame -q:a 0 18380889311644327118.mp3


  


  -i specifies the input file
-vn disables all video-streams from the input
-ar audio sampling frequency
-ac number of audio channels
-b:a bit rate
-c:a libmp3lame - codec of target file
-q:a quality set audio quality (codec-specific) (lower is better), see https://superuser.com/a/1515841

-sn disables all subtitle-streams from the input
-dn disables all data-streams from the input


  


  The console output looks like this :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '18380889311644327118':
  Metadata:
    major_brand     : iso5
    minor_version   : 1
    compatible_brands: isomiso5hlsf
    creation_time   : 2021-12-08T15:44:06.000000Z
  Duration: 00:00:01.00, start: 0.000000, bitrate: 2258 kb/s
    Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 2234 kb/s (default)
    Metadata:
      creation_time   : 2021-12-08T15:44:06.000000Z
      handler_name    : Core Media Audio
Stream mapping:
  Stream #0:0 -> #0:0 (aac (native) -> mp3 (libmp3lame))

Output #0, mp3, to '18380889311644327118.mp3':
  Metadata:
    major_brand     : iso5
    minor_version   : 1
    compatible_brands: isomiso5hlsf
    TSSE            : Lavf58.29.100
    Stream #0:0(und): Audio: mp3 (libmp3lame), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2021-12-08T15:44:06.000000Z
      handler_name    : Core Media Audio
      encoder         : Lavc58.54.100 libmp3lame
size=      17kB time=00:00:01.01 bitrate= 135.5kbits/s speed=37.2x
video:0kB audio:16kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 3.343701%


  


  As you can see, the duration is 01.00 second. And this happens with all recorded files.

  


  How to convert the entire file (which is 12 seconds long) to its full length ?

  

  

  


  Note : It seems that the recorded file does not have a length specified. Under Windows I renamed the file, adding an extension ".m4a" and opened the file properties :

  


  

  


  The length attribute is empty.

  


• Is there any way to get the exact audio .wav from a .mp4 video ? (same length and same duration)

  25 novembre 2022, par yuan gan

  I extracted .wav files from many short mp4 videos. (3-6 seconds) But the extracted xxx.wav can not be aligned with .mp4 videos in Premiere. Some videos are 1 frame, and some 2 frames behind.

  


  I used ffmpeg as the following command line :

  


  ffmpeg -i xxx.mp4 xxx.wav

  


  I tried -async or -vsync, but not worked. Here is an example :
1 frame shift

  


  Here is the source mp4 and the extracted wav :
https://drive.google.com/drive/folders/1BFS0JLCPqA3YDMIahlorXTaRTFTJaPfU?usp=share_link

  


  Do you know what caused the problem ? Is there any way to get the exact audio .wav from a .mp4 video ? (Aligned with frame level) Thank you very much.