Simon MacDonald created CB-1211:
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Summary: Media record uses a .mp3 extension when it is a .3gp file
Key: CB-1211
URL: https://issues.apache.org/jira/browse/CB-1211
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 mp3.
I opened the generated file(which was playable with correct sound) and found
something interesting:
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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