Playback issues with RTP sample recordings

[dsilhavy]

Moved from #21

Description

When playing the recordings downloaded from web page
https://github-wiki-see.page/m/Austrian-Broadcasting-Services/obeca-info/wiki/sample-files

and from these files, the only recording that we could play smoothly is
5MHz_MCS16_1kHz25_RTP_3.5.raw

a little worse is
5MHz_MCS16_7kHz5_RTP_3.5.raw

the following files can be decoded using
modem -f file-name -b x

10MHz_MCS16_1kHz25_RTP_3.5.raw
3MHz_MCS16_1kHz25_RTP_3.5.raw
6MHz_MCS16_1kHz25_RTP_3.5.raw
7MHz_MCS16_1kHz25_RTP_3.5.raw
8MHz_MCS16_1kHz25_RTP_3.5.raw

but on vlc the playback is jerky (interruption every 1 – 2 second in video and sound).

[dsilhavy]

Comment from Klaus:

As preparation for a call with @m-bures this morning, I downloaded and tested the 10MHz sample file (https://obeca-testdaten.s3.eu-central-1.amazonaws.com/10MHz_MCS16_1kHz25_RTP_3.5.raw)

I can confirm that it has playback issues (stalls in audio and video every one or two seconds), even though the modem reports no CRC errors, and neither Wireshark nor VLC display RTP packet loss or sequence discontinuities.

VLC shows no actual errors, but "playback way too early"-warnings.

[dsilhavy]

I did some checks with https://obeca-testdaten.s3.eu-central-1.amazonaws.com/3MHz_MCS16_1kHz25_RTP_3.5.raw and there are a lot of decoding errors when playing with ffplay. I will download some of the other files as well but we probably need new recordings.

[dsilhavy]

Some detailed results

3MHz_MCS16_1kHz25_RTP_3.5.raw

• Decoding artifcats and ffplay errors

[h264 @ 0x7f7fa01c6640] left block unavailable for requested intra4x4 mode -1
[h264 @ 0x7f7fa01c6640] error while decoding MB 0 17, bytestream 11322
[h264 @ 0x7f7fa01c6640] concealing 529 DC, 529 AC, 529 MV errors in I frame
[h264 @ 0x7f7fa01c6640] left block unavailable for requested intra4x4 mode -1
[h264 @ 0x7f7fa01c6640] error while decoding MB 0 16, bytestream 486
[h264 @ 0x7f7fa01c6640] top block unavailable for requested intra mode -1
[h264 @ 0x7f7fa01c6640] error while decoding MB 44 23, bytestream 4744

[aac @ 0x7f7fa0020e40] Number of bands (56) exceeds limit (39).0/0
[aac @ 0x7f7fa0020e40] Multiple frames in a packet.
[aac @ 0x7f7fa0020e40] Prediction is not allowed in AAC-LC.

5MHz_MCS16_1kHz25_RTP_3.5.raw

• seems to run stable
• No errors in ffplay once playback started

6MHz_MCS16_1kHz25_RTP_3.5.raw

• seems laggy like playbackrate < 1, slow-mode?
• No concrete errors in ffplay once playback started
• ffplay shows a drift between Audio and Video. For the 5MHz file the drift is around 0.0. For this file it is between 0.5 - 1.5

7MHz_MCS16_1kHz25_RTP_3.5.raw

• seems laggy like playbackrate < 1, slow-mode?
• No concrete errors in ffplay once playback started
• ffplay shows a drift between Audio and Video. For the 5MHz file the drift is around 0.0. For this file it is between 0.5 - 1.5

10MHz_MCS16_1kHz25_RTP_3.5.raw

Segmentation fault

[dsilhavy]

As part of the work on Rel.17 support and release 2.0.0 we should do new recordings. Potentially, @alessandro-lucco can help here.

[dsilhavy]

@alessandro_lucco confirmed that he can provide some recordings for Rel 16. Once the changes from @kuehnhammer are merged we evaluate these recordings against the implementation. Once the recordings work, we upload them to our Linode or Github LFS.

[Huihui1982]

Could you provide some recordings for Rel 16 now?I am also do the same development from Rel -14 to Rel-16. I have add the PBCH repetition , Aggregation level 16 and CFI-indicator in MIB-MBMS . I used test file "5MHz_MCS16_1kHz25_HLS_q4a_Rel16.raw" downloaded from "https://github.com/5G-MAG/Getting-Started/wiki/Sample-Files#sample-files-for-rt-mbms-modem-development-rel14rel16-only" and the result is similar to " Rel-16 CAS support on rt-mbms-modem (1.2.0) ? #31 ", it gets synced, shows correct information about PDSCH channel but no information about MCH and no stream on the output.@dsilhavy

[dsilhavy]

@Huihui1982 The Rel.16 and Rel.17 changes in the MBMS Modem and the MBMS MW are currently being finalized. We will probably have a presentation on that in the next public call on 29.3.24: https://www.5g-mag.com/community Once the changes are tested and merged we will provide new sample recordings that match the implementation.

Maybe @alessandro_lucco already has something he can share if you have your own implementation of MBMS Modem and MW.

[alessandro-lucco]

Could you provide some recordings for Rel 16 now?I am also do the same development from Rel -14 to Rel-16. I have add the PBCH repetition , Aggregation level 16 and CFI-indicator in MIB-MBMS . I used test file "5MHz_MCS16_1kHz25_HLS_q4a_Rel16.raw" downloaded from "https://github.com/5G-MAG/Getting-Started/wiki/Sample-Files#sample-files-for-rt-mbms-modem-development-rel14rel16-only" and the result is similar to " Rel-16 CAS support on rt-mbms-modem (1.2.0) ? #31 ", it gets synced, shows correct information about PDSCH channel but no information about MCH and no stream on the output.@dsilhavy

Hi @Huihui1982, sure, I can record some test streams, I'll try to share something with you next week.

[Huihui1982]

Thank you very much@alessandro-lucco，Looking forward to your sharing.

[dsilhavy]

@Huihui1982 : @alessandro-lucco created some sample recordings they are available here:

• https://rt.5g-mag.com/mbms/example-recordings/HLS_Rel14_MCS12_cut.raw
• https://rt.5g-mag.com/mbms/example-recordings/HLS_Rel16_MCS12_cut.raw
• https://rt.5g-mag.com/mbms/example-recordings/TS_Rel14_MCS12_cut.raw
• https://rt.5g-mag.com/mbms/example-recordings/TS_Rel16_MCS12_cut.raw