HydrogenAudio

Lossy Audio Compression => AAC => AAC - Tech => Topic started by: mp4_Programmer on 2013-04-19 15:07:57

Title: Mp4 bit rate extraction from its metadata
Post by: mp4_Programmer on 2013-04-19 15:07:57
Hi All,


i am trying to extract the bitrate of a mp4 file problematically but could not. can some one please let me know how we can find the bit rate of the mp4 file.
I tried searching on google but could not find much.

I have few queries :

1. Is bitrate stored in the file in some atom.
2. If not do we have any standard formula to calculate the bitrate.

Any help would be highly appreciated.

Thanks in Advance.
Title: Mp4 bit rate extraction from its metadata
Post by: greynol on 2013-04-19 15:11:13
Why was this dumped in the General Audio Forum when we have one dedicated for aac?

Did you read the rules that were presented to you when you registered?
Title: Mp4 bit rate extraction from its metadata
Post by: db1989 on 2013-04-19 15:15:04
By “mp4”, should we assume that you specifically mean AAC? MP4 is only a container, which can encapsulate MP4, MP3, or other formats. Whichever format you are referring to, is it CBR or VBR? If it’s CBR, you might find the bitrate already supplied in a field such as avgBitrate (http://forum.doom9.org/archive/index.php/t-164360.html) (from a quick search on Google). If such a field is not available and/or if the stream is VBR, chances are you will have to perform the calculation yourself from the duration of the stream and size of the file (corrected for metadata and other forms of padding if you want to be really accurate). In any case, I suspect the information is already available, but perhaps other users can repost it here.

Edit: My first question was related to what greynol has said, but I decided to wait for confirmation before pointing that out. If you are talking about AAC, this should go in the subforum so-named. In any case, the format in question is the kind of basic element that you need to specify when asking questions; people can only guess otherwise, which is not very productive for anyone involved.
Title: Mp4 bit rate extraction from its metadata
Post by: mp4_Programmer on 2013-04-19 15:29:33
Will move this to ACC.

Thanks, n Yes its ACC.
Title: Mp4 bit rate extraction from its metadata
Post by: greynol on 2013-04-19 15:32:39
You cannot move it, that work has to be done by a member of the staff.

Why was this double-posted to the A/V sub-forum?

Please don't now triple-post.