Thanks in contributing to the project with your patches. Right now, the only easy method is by using an USB dongle. The next firmware will be based on official 0.32 firmware which have 1M of permanent memory.
This partition is shared by network (NFS and maybe Samba for windows users) and if you put a "patch.zip", it extracts it and patch the firmware...so everyone could easily modify the datv firmware for testing.
73 EVariste F5OEO
Yes Mike, the most efficient way would be to offline encode the video (double pass encoding) and replay it with PCR/PTS correction (for continuous time over loop). For that , it needs an input TS file on the modulator side which is not the case on the current system as it is design for HDMI live encoding purpose. This is a choice of the team...
Just to confirm same analysis here :
Stream is not ETR290 compliant. PCR accuracy is +/- 800us instead of +/-500ns. It is not very smart but should not be too disturbing.
Profession Dectek StreamXpert is used to do that, which is equivalent to your R&S for this kind of measure.
The main issue, is effectively the -500 ms of PCR/PTS (It is not measured by ETR290). This means that decoder is asked to display a picture which is not yet arrived (500ms late). Strategy of decoders to handle this issue depending on the decoder.
VLC for example, try to increase the input buffer in order to display later pictures :
"
main warning: picture is too late to be displayed (missing 281 ms)
main warning: picture is too late to be displayed (missing 259 ms)
main warning: picture is too late to be displayed (missing 250 ms)
main warning: picture is too late to be displayed (missing 230 ms)
main warning: picture is too late to be displayed (missing 210 ms)
main warning: picture is too late to be displayed (missing 190 ms)
"
SF8008 could have also this strategy..but it is a workaround. As clock is not precise, we could then have some issue between audio/video synchronisation.
Professional decoders (Tandberg, Scopus ...) doesn't allow for such errors and do not display a picture at all.
This issue has already been seen regularly with 2MS beacon, and was recovered by a reset of the encoder/modulator.
It seems that at 1.5MS the issue could happen more regularly.
Right now, it seems that the beacon is performed by Raspberry looping a video and output it to HDMI whish is then H264 encoded and modulated by SR System. The system could drift over time and could explain such errors (long term stability is not so easy in DVB).
We hope that we could make analysis just after a reset to confirm this analysis.
As Mike said, we are a community which include experts (DVB for example). Goal is to experiment and improve system..thus, could interesting to discuss and exchange with "The" team to share knowledge when we have such issue.
73 Evariste F5OEO
Quick test with EasyCap analog video input dongle : 75%CPU at H264 352x288 resolution and audio AAC at 500Ksymbol DVBS2.
So this is the proof of concept with ONLY plutoSDR and this usb stick.
We could also build a solution with Analog to HDMI -> HDMI to H265 encoder box (60euro) -> usb ethernet ->PlutoSDR which is completely autonom but with a much better quality.
Evariste
PlutoSDR has an embedded CPU : NO computer is needed (STANDALONE). It could start Tx as soon as it is power on.
Modulation parameters are keep in flash, meaning always the same over reboot.
SR from 125 to 1000 is possible. CPU processing is limited, so encoding HD is not possible but as it is an SD analog input it should be OK. I need to make more tests on that. Will inform you soon.
Do you mean standalone device for Analog video input (composite or s-video) to DVBS/S2 modulator ?
Need litlle work, but
- PlutoSDR
- USB Analog video Stick
- One time configuration through web interface
- You are QRV DATV 40Mhz-6Ghz
73 F5OEO
