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From "Simon MacDonald (JIRA)" <>
Subject [jira] [Resolved] (CB-1211) Media record uses a .mp3 extension when it is a .3gp file
Date Wed, 08 Aug 2012 19:36:21 GMT


Simon MacDonald resolved CB-1211.

    Resolution: Fixed

Temp file extension is now .3gp.
> Media record uses a .mp3 extension when it is a .3gp file
> ---------------------------------------------------------
>                 Key: CB-1211
>                 URL:
>             Project: Apache Cordova
>          Issue Type: Bug
>          Components: Android
>    Affects Versions: 2.0.0
>            Reporter: Simon MacDonald
>            Assignee: Simon MacDonald
>            Priority: Minor
>             Fix For: 2.1.0
> Hi, I am analyzing the files generated on SD card after the completion of recording.
> The recording is implemented using "my_media.startRecord();". 
> So I looked into the Java code of Cordova and found that PhoneGap will create something
called "tmprecording.mp3" and I assume that PhoneGap encodes the output of the recording in
> I opened the generated file(which was playable with correct sound) and found something
> 1. It was neither one of MEPGI/II/III. The first 11 bits of the file I got are all 0s.

> 2. It was not a .wav file. The first four bytes should be "RIFF" in ASCII for a legal
.wav file, which was not the case on the file I got. 
> For project requirement, I need to verify the sampling rate and bit rate of the mp3 file
generated. However, even though I use some mp3 checker software, I cannot retrieve these information
from the file generated. 
> After that I use the media player to play the file, and tried monitoring which decoder
the player used, and got the following information:
> Input: amrnb, mono, 8000 HZ, 128kbps (libavcodec)
> Output:  PCM, Stereo, 8000HZ, 16-bit integer
> Is that the correct information I wanted to know? Which one of them indicates the correct
sampling rate and bit rate? Does anyone know what format specifically the recorded file is
and where I can find its spec(such as header, etc)?
> Later I need to manipulate the recorded file (e.g., retrieve simple waveform). Really
appreciate your help.
> I don't know if it is only me(HTC One X and Nexus Glaxy) or everyone, but the file format
is eventually confirmed as MP4/3GP. The file I got from PhoneGap recording is encoded with
3GP release 4 codec because it has the header "00 00 00 18 66 74 79 70 33 67
> " in hex. This seems very different from a MPEG-3 file format and I don't understand
why PhoneGap Cordova team will name such file as *.mp3. Is this behavior system/browser-related
on different device or universal to all Cordova apps?

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