It indeed seems that overflow is the reason here:
The PAD size of 24 results in:
- 2 bytes F-PAD, signalling the X-PAD
- (up to) 22 bytes X-PAD
Due to DAB restrictions on the X-PAD Data Group sizes, rather 20-21
bytes can be used for actual Slideshow/DLS payload.
The DLS is inserted every 50 PAD packets during transmission of a slide.
In your case of 48kHz MP2, this corresponds to every 1200ms.
So:
10299 bytes plus assumed 10% overhead....= 11329 bytes.
With 21 bytes usable X-PAD, this results in 539 X-PADs needed.
Every 50th X-PAD DLS is inserted, which takes ~7 X-PADs (assuming 128
bytes plus some overhead). So 43 X-PADs remain for the Slideshow until
the DLS is inserted again.
539 / 43 = 12,5 iterations
12,5 * 50 = 626,7 X-PADs for a single slide pass
626,7 * 0,024 = 15,04s
So 16s should be sufficient in theory, maybe use 17s just to make sure.
Another question is then why the problem did not already occur with v2.1.1.
Regards,
Stefan
Am 06.06.2017 um 17:30 schrieb Nick Piggott:
> Switching to --sleep=15 has improved it.
>
> How many bytes are allocated to DLS relative to Slideshow in the new method?
>
> My original calcs were *fairly* tight (10299 bytes file, plus MOT
> overhead (10%) plus 128 bytes DLS = 11.5 seconds). Maybe it was
> overflowing and filling the buffers?
>
>
> Nick
>
>
> On Tuesday, 6 June 2017 16:10:05 UTC+1, Nick Piggott wrote:
>
> Hi,
>
> I've currently got a static slide on there, so I'll need to create a
> variant version and swap between the two. I'll try that tonight.
>
> The command lines are:
>
> odr-padenc --output /home/dabsys/site/mot/station.mot --dls
> /home/dabsys/site/mot/station.txt
> --dir=/home/dabsys/site/mot/slideshow/station --raw-slides --pad=24
> --sleep=12
> odr-audioenc --dab --bitrate=128 --dabmode=j --dabpsy=2 --pad=24
> --pad-fifo=/home/dabsys/site/mot/station.mot --input=/dev/stdin
> --output=tcp://
127.0.0.1:9001 <
http://127.0.0.1:9001>
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