Hello all,
We're currently using a custom DM355 board running DVSDK
1.30 with following intended goals (all simultaneously done):
1) video encode at 30fps (NTSC), MPEG4 encoded and stored to a USB
Mass storage flash drive (~3.33Mbytes/sec writes measured)
2) video decode at 30fps (NTSC), MPEG4 encoded and retrieved from
the same USB flash drive
3) audio storage of 32Khz 16-bit audio to file on USB flash drive
4) audio playback of 32Khz 16-bit audio from USB flash drive
I've got the complete application running on the ARM with ~50% loading,
with minimal memory copies as possible. All filesystem writes/reads are
optimized to be at 8192 byte sizes to ensure maximum throughput, and
we're using the resizer to accomplish memory copies. There are separate
threads for filesystem writes/reads, and the actual decode/encode
threads for both audio and video so that any filesystem hits don't
impact the flow of data.
Currently, audio works absolutely fine with the buffering, and video
encode works fine as well. However, when I do video decode, I'm noticing
very stuttery video display on the screen at moments. I verify that the
display thread has adequate buffers pooled up for it, so I'm not sure
where the stutter is coming from. The latter point also rules out
filesystem slow-downs since I'm adequately feeding the decode threads
with up to 1MB of cached data. The display thread is the highest
priority thread in the system, so it should be pre-empting every other
thread in the system. This stuttery display reduces somewhat if audio
in/out is disabled, but is still slightly present. There is also tearing
on the screen as well.
If I run the decode demo, I do not get any problems.
Any clues?
Thanks a ton,
Jerry Johns
Design Engineer
Nuvation Research Corp - Canada
Tel: (519) 746-2304 ext. 225
www.nuvation.com <http://www.nuvation.com>
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