03-28-2008 06:35 AM
I have long sought a solution for scheduling recording from my DAB radio as I'm always busy when my favourite shows are broadcast.
Methods I have tried are:
Wavefinder device (no good as it requires a PC to be left on all the time)
Plug in USB DVB device (much easier to schedule but same 'PC must always be on' problem.)
The V-Mate seems promising but looks like it may only record video formats (no good for either of my portable MP3 players.
Has anyone tried to record audio only on their V-Mate?
Does anyone know of any similar products which may offer a solution?
Solved! Go to Solution.
03-31-2008 05:17 AM
The V-Mate only records in MP4 (ISO), MP4 (PSP), 3GP and 3G2 formats.
Would it work for recording radio... maybe, but the radio would have to output to a RCA jack and the V-Mate would assume it is recording video and save to those formats, with playback being a blank screen and the audio.
If you then converted it to MP3... not sure what would happen, or if you can even find a converter to do that.
08-27-2009 10:06 PM
You said, "If you then converted it to MP3... not sure what would happen, or if you can even find a converter to do that."
Adobe Audition can do that. It has a function in it to extract the audio from a video file. Then you can save that in any format you want, practically.
Come to think of it, many video editing programs will also allow you to output an audio file extracted from a video source file.
08-28-2009 07:14 AM
There is no question that you can record audio using V-Mate, there are just some issues to be dealt with.
One is the sound quality. If you want the best that the V-Mate is capable of, from my test recordings of all the formats the V-Mate is capable of (21 for mp4(ISO), 3 for mp4(PSP), 9 for 3g2, and 9 for 3gp), the best internally documented quality seems to be using any of the mp4(ISO) settings. All of them use AAC LC (Advanced Audio Coding - Low Complexity) at 64 kbps bitrate and 32 kHz frequency. To keep the size of the created mp4 file to a minimum, use the lowest quality video settings: Quality = Best, Resolution = 128x96, and Frame Rate = 15. The mp4(PSP) settings all use an internally documented AAC LC at 64 kbps/24kHz and the 3gp/3g2 settings all use AMR (Adaptive Multi-Rate compression) at 13kbps/32kHz.
I'm not sure whether it is best to leave the Yellow composite video input connector unconnected or connected to a video source that does not change (like a black (or blue) screen). If you try some tests in this area, please let us know your findings...
Another issue is do you leave the audio at AAC/AMR or do you convert to MP3? If you convert will that adversely affect either the sound quality or file size? (Let us know!)
One final issue is the possibilty of creating an mp4 file which contains mostly the original audio (maybe edited somewhat to improve it) but with a pleasing video still photo to take the place of a black/blue screen. I suspect this should be possible w/ software, but I don't have anything from experience to recommend.
There exists a freeware command-line interface program named MP4Creator (see http://mp4creator.sourceforge.net/ for download and documentation) that can extract the .aac audio file from a V-Mate created .mp4 file using the following command (assuming an input file named 09-0101.00.00.00.mp4 and an output file named 09-0101.00.00.00.aac):
mp4creator -extract=1 09-0101.00.00.00.mp4 09-0101.00.00.00.aac
Note: the -extract=1 parameter identifies that you want to extract the 1st "track" of the .mp4 file (which for the V-Mate's .mp4 files will always be the audio track (and the 2nd track is always the one with the video)). This .aac sound file can be played using Winamp (and probably other programs, but I haven't tested any others).
This MP4Creator program has other uses and I will try to report on them here at a later time. I'm sorry I don't have the name of a program to convert from an .aac file to an .mp3 file at this time either.
Message Edited by MikeDuffy on 08-30-2009 08:24 PM
08-28-2009 07:00 PM
hckrs2k3: I don't understand your post: could you please elaborate? Also please go beyond a single sentence.
It is not uncommon for some of my posts take hours to research and to write as completely and clearly as I can (even at the cost of excessive dryness). I value this forum as a place I can learn and share information on issues concerning the V-Mate, since the published documentation "leaves something to be desired".
To summarize: readers of this forum including me value more information, not less. Please hckrs2k3, live up to your "SanDisk Professor" title. Please provide much more information when you post, i.e. more quality of posts than quantity of posts.
08-31-2009 06:37 AM
MikeDuffy - Thanks for the in depth info on audio.
I have extracted audio from a V-mate file using MPEG Streamclip, a Mac utility. I've found the audio quality suffers a lot in the transformation from MP$ video to MP3 audio. I will try some of your settings and see if I can optimize the sound quality.
MPEG Streamclip is a Mac graphical front end for the ffmpeg conversion libraries. They do conversions between codecs and audio extractions. There are free Windows (Do a Google search for "ffmpeg Windows") and of course Linux versions.
08-31-2009 12:32 PM
makuribu: I don't know nearly as much as I would like to about audio and video files, but I have done a fair amount of examining the V-Mate's .mp4 output using a hex editor. If I recall correctly, it appears that the MP4Creator program (in the example I gave previously) just extracts the aac elemental audio as is and does no "conversion" of any kind, i.e. there should be no change in audio quality from the original .mp4 file.
I have no experience with the various audio/video editing programs so I can't (yet) suggest one that does a good job of converting from .aac files to .mp3 files. It may happen that a/v players will improve over time to include support for a number of audio/video formats and so there will be less of a need to convert from one format to another (except for maybe a desire to compress content with minimal/acceptable loss of quality).