Topic: Portable Larvy AD10?

[Colin Liston]

Bump to the top.

[anechoic]

I just do not know how many people with portable recording applications have a requirement for the highest sound quality.

film sound effects, ENG, video, etc.
I'd say the market is there and growing weekly as evidenced by the amount of portable digital recorders coming to market

[jerryfreak]

keep in mind that 8gb SDHC is like $10, and 16 and 32 gb  are cheap and common these days, so double or x4 those times for most users

sdhc is small, cheap, and efficient, is currently my media of choice (16GB in the size of a postage stamp, for $50 , and falling every day, are you kidding?!?) we dreamed about this years ago!

im sure sdhc is much cheaper to implement than a hard-drive that sucks power and creates heat.

a lot of people love the sound devices unit, but imo that unit could be improved if the cost savings from eliminating features like the (redundant) hard drive setup could be used toward better sounding conveters and pres. I'm big on simple, clean sound with LESS bells and whistles. 

How much capacity for stereo?

Regards
Dan Lavry 

Credit to Rick in another thread for posting:

Recording Time using 8 GB SDHC card   
16 bit/44.1kHz : 755 minutes (Stereo), 377 minutes (4ch)
16 bit/48kHz : 694 minutes (Stereo), 347 minutes (4ch)
24 bit/48kHz : 462 minutes (Stereo), 231 minutes (4ch)
24 bit/96kHz : 231 minutes (Stereo), 115 minutes (4ch)
24 bit/192kHz : 115 minutes (Stereo)

http://taperssection.com/index.php/topic,97214.msg1342757.html#msg1342757

--Michael

[jerryfreak]

most sdhc out there is typically 'class 4' or 'class 6' (4-6MB/sec minimum speed),

so with some buffering, they handle all commmon audio data streams fine

16/44.1 @ 2channel = 1411 kbit/sec= 1.411 mbit/sec = 0.176 MB/sec
24/26 @ 4-channel = 9216 kbit/sec= 9.216 mbit/sec = 1.15 MB/sec

SDHC is smaller and cheaper than compact flash, is plenty fast, and becoming more common every day

I checked the possibility of puting audio data on "memory sticks", and sadly enough, those devices are too slow for recording data in. A few of them are fast enough for an uncompressed playback at CD speed... 
Flash ram is great, but it does have it's limitations. Writing in (recording) must be preceeded by a process of earsing, which slows the whole thing down a lot...

That leaves us with other memory types. Looking at CF memory, I wonder what are the most popular formats for "putting audio" such on CF memory for use in portable gear? Does ALL the gear that comes with CF require the use of specific software to be installed on the computer? Is there some "generic" software driver for downloading the audio from CF to the computer? Clearly, one needs to know the sample rate and the bit length of the data...

I would appreciate answers to the question.

Regards
Dan Lavry

[jerryfreak]

well ideally, you are transferring the recorded wav file as a file, not real time. there is no resampling, reclocking, etc. if your device records 24/96, that is stored in the wav header, and its just a file copied via usb2 speeds. i dont know anybody that uses real-time playback to transfer from flash-based recorders.

in regard to developing software for writing datastreams, gordon needs to enter this thread.

Thanks for the replies.

Using WAV files is fine with me, and USB is great for data transfer.
I also like non proprietary formats.

With real time transfer, I was under the impression that unless one is clever enough, Windows defaults to 16 bits. This is not exactly my area of expertise... But here we are just copying files so I would want to provide up to 24 bits, at sample rates from 44.1 to 96KHz. Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case. Or does the user "just knows" how the recorder was set up?
There is much here for me to be learned...

Regards

Dan Lavry

[live2496]

On pocket pc's it has been my experience that CF cards and SD cards are both adequate. We have had problems sustaining 24/96 to CF cards, but I think this was largely due to the requirement of passing the data through a 16-bit PCMCIA interface to get the data to the storage device. (SoundDevice's recorders use CF cards.) 

On newer machines we have used 150x SD media with excellent results.

How does the user preference of sampling rate, etc get passed from the mic A>D to application software?
In our case it was a question of transmission over SPDIF. You can auto-detect the rate from the SPDIF stream (SPDIF receiver chips can do that), or you can let the user set it to whatever they want and require that the transmission rate and SPDIF receiver's rate match. I made a design choice to implement both. The user can lock onto the sampling rate of the transmitting chip or set it to a specific rate. If the application is expecting a specific rate and it's something different you get an error.