MP4 sound sync issues

General Gen8 Archos Tablet discussions
Post Reply
FSki
Archos User
Archos User
Posts: 119
Joined: Fri Dec 09, 2005 10:45 pm

MP4 sound sync issues

Post by FSki »

I use Get I Player to download BBC I Player programs so I can play them on my Archos 101, however while the native files play the sound slowly goes out of sync with the video and after 30 mins or so the sound is a few seconds behind the video, I can cure this by changing them to AVI files and then DMux'ing them. But is there something I can do to get the original files to play properly rather than have to post process them on my computer.

If I play the native MP4 files back on my Windows XP PC using VLC they play OK.
julian67
Archos Expert
Archos Expert
Posts: 218
Joined: Thu Feb 03, 2011 2:33 pm

Re: MP4 sound sync issues

Post by julian67 »

I have the same issue with get_iplayer .mp4 video files, and I found the same thing when using the iplayer app or using the iplayer site in a web browser on the A43. I recall seeing BBC iplayer videos as being problematic in this respect on quite a lot of devices, though I don't have a reference to hand. What I do is mux the files into mkv and then transfer them to my A43. mkv is a better choice of container than .avi for the combination of h.264 video and aac audio. I don't think there's any way of getting a good viewing experience on the A43 with these files except by remuxing them.

To mux into .mkv the easiest way is to use mkvmerge, which is part of the mkvtoolnix suite. It's free software, and a Windows version can be obtained from http://www.bunkus.org/videotools/mkvtoo ... ml#windows
FSki
Archos User
Archos User
Posts: 119
Joined: Fri Dec 09, 2005 10:45 pm

Re: MP4 sound sync issues

Post by FSki »

Brilliant, thank you, and so quick too. Much appreciated.
nz
Archos Staff
Archos Staff
Posts: 712
Joined: Thu Jul 26, 2007 6:17 pm
Location: Archos SA, France
Contact:

Re: MP4 sound sync issues

Post by nz »

FSki wrote:I use Get I Player to download BBC I Player programs so I can play them on my Archos 101, however while the native files play the sound slowly goes out of sync with the video and after 30 mins or so the sound is a few seconds behind the video, I can cure this by changing them to AVI files and then DMux'ing them. But is there something I can do to get the original files to play properly rather than have to post process them on my computer.

If I play the native MP4 files back on my Windows XP PC using VLC they play OK.
can you provide a sample file?
julian67
Archos Expert
Archos Expert
Posts: 218
Joined: Thu Feb 03, 2011 2:33 pm

Re: MP4 sound sync issues

Post by julian67 »

I can supply a clip. I cut a 2 minute sample from a get_iplayer .mp4 video. get_iplayer uses ffmpeg to mux from the BBC flv to mp4 container. I performed the cut on the same machine using ffmpeg (same version of course) like so:

Code: Select all

ffmpeg -ss 300 -t 120 -i Inside_Men_-_Episode_3_b01c8crd_default.mp4 -acodec copy -vcodec copy -y Inside_Men_-_Episode_3_sample.mp4
All metadata is retained. The resulting file plays back perfectly on PC but on A43 the audio is badly out of sync. However using mkvmerge to remux the same 2 minute clip into matroska container gives perfect a/v sync on my A43IT: same audio, same video, same metadata, only the container is different.

I'm sending you the links to the clips via pm as I'm using a free file host without signing up to it, and I have no idea about any limitations it may have on number of downloads, bandwidth etc for unregistered users. Please feel free to post the links here after you have obtained the files, if you like.
julian67
Archos Expert
Archos Expert
Posts: 218
Joined: Thu Feb 03, 2011 2:33 pm

Re: MP4 sound sync issues

Post by julian67 »

The latest firmware 2.4.83 completely solves this issue. mp4 files downloaded using get-iplayer now play with perfect audio sync and stay in sync. Thanks to the Archos devs for the bugfix.
Post Reply

Return to “General Archos Gen8: Archos 28, 32, 43, 70 and 101 Internet Tablets”