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SubjectRe: [v10 0/4] media: vidtv: Implement a virtual DVB driver
Hi Daniel,

Em Fri, 21 Aug 2020 09:58:44 -0300
"Daniel W. S. Almeida" <dwlsalmeida@gmail.com> escreveu:

> From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
>
> This series is work in progress. It represents the current work done on a
> virtual DVB driver for the Linux media subsystem. I am new to the media
> subsystem and to kernel development in general.
>
> This driver aims to:
> - Serve as template for new DVB driver writers
> - Help userspace application writers in general
> - Push fake audio/video to userspace for testing
> purposes
> - Push debug information to userspace via debugfs
>
> Current state for this driver:
> - Driver generates PSI information (PAT, PMT, SDT)
> - Driver generates PCR packets
> - Driver generates NULL packets for padding
> - PCM audio stream is decoded by ffmpeg, but no audio is heard yet.
>
> changes in v10:
> s302m encoder got reworked

Thanks for all the hard work on it. Very much appreciated!

I finally found some time to test it. For now, just a quick
test from my side, without passing any arguments to the
driver.

See enclosed.

While there are still a few issues there, I'm considering applying
this series for Kernel 5.10.

My plan is to write some patches on the top of yours, in order to
address the problems I'll find on it. If not something more critical
won't be solved in time, we may still add it at staging/media.
Let's see.

The problems I noticed so far are:

1. rmmod doesn't work;
2. dvbv5-stats doesn't seem to be working properly, as
it is reporting signal strengh with a percentage
(same for Carrier S/N ratio);
3. dvbv5-zap wrote an empty audio file (without -P flag).
Probably there are still some issues at the program
channel descriptor or service;
4. The provider service field is null. Perhaps we could
add some string there, like "linuxtv.org".
5. Maybe we could also add a simple NIT table, just to
avoid dvbv5-scan to wait for it until timeout.

Also, it probably makes sense to add a debugfs interface in
order to allow injecting errors at the stream at runtime.

Regards,
Mauro

---

$ dvbv5-scan -v foobar
using demux 'dvb0.demux0'
Device Dummy demod for DVB-T/T2/C/S/S2 (/dev/dvb/adapter0/frontend0) capabilities:
CAN_FEC_1_2
CAN_FEC_2_3
CAN_FEC_3_4
CAN_FEC_4_5
CAN_FEC_5_6
CAN_FEC_6_7
CAN_FEC_7_8
CAN_FEC_8_9
CAN_FEC_AUTO
CAN_GUARD_INTERVAL_AUTO
CAN_HIERARCHY_AUTO
CAN_INVERSION_AUTO
CAN_QAM_16
CAN_QAM_32
CAN_QAM_64
CAN_QAM_128
CAN_QAM_256
CAN_QAM_AUTO
CAN_QPSK
CAN_TRANSMISSION_MODE_AUTO
DVB API Version 5.11, Current v5 delivery system: DVBC/ANNEX_A
Supported delivery systems:
DVBT
DVBT2
[DVBC/ANNEX_A]
DVBS
DVBS2
Frequency range for the current standard:
From: 51.0 MHz
To: 2.15 GHz
Step: 62.5 kHz
Tolerance: 29.5 MHz
Symbol rate ranges for the current standard:
From: 1.00 MBauds
To: 45.0 MBauds
Failed to guess country from the current locale setting.

ERROR command BANDWIDTH_HZ (5) not found during retrieve
Cannot calc frequency shift. Either bandwidth/symbol-rate is unavailable (yet).
Scanning frequency #1 330000000
FREQUENCY = 330000000
MODULATION = QAM/AUTO
INVERSION = AUTO
SYMBOL_RATE = 6940000
INNER_FEC = AUTO
DELIVERY_SYSTEM = DVBC/ANNEX_A
Got parameters for DVBC/ANNEX_A:
FREQUENCY = 330000000
MODULATION = QAM/AUTO
INVERSION = AUTO
SYMBOL_RATE = 6940000
INNER_FEC = AUTO
DELIVERY_SYSTEM = DVBC/ANNEX_A
Lock (0x1f) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0
dvb_read_sections: waiting for table ID 0x00, program ID 0x00
dvb_parse_section: received table 0x00, extension ID 0x0744, section 0/0
dvb_parse_section: table 0x00, extension ID 0x0744: done
PAT
| table_id 0x00
| section_length 13
| one 2
| zero 0
| syntax 1
| transport_stream_id 1860
| current_next 1
| version 1
| one2 3
| section_number 0
| last_section_number 0
|\ 1 program pid
| pid 0x0101: service 0x0880
Program #0 ID 0x0101, service ID 0x0880
dvb_read_sections: waiting for table ID 0x02, program ID 0x101
dvb_parse_section: received table 0x02, extension ID 0x0880, section 0/0
dvb_parse_section: table 0x02, extension ID 0x0880: done
PMT
| table_id 0x02
| section_length 24
| one 2
| zero 0
| syntax 1
| transport_stream_id 2176
| current_next 1
| version 1
| one2 3
| section_number 0
| last_section_number 0
|- pcr_pid 0200
| reserved2 7
| descriptor length 0
| zero3 0
| reserved3 15
|\
|- stream 0x0111: ISO/IEC 13818-1 Private Data (6)
| descriptor length 6
| 0x05: registration_descriptor
| 42 53 53 44 BSSD
|_ 1 streams
dvb_read_sections: waiting for table ID 0x40, program ID 0x10
ERROR dvb_read_sections: no data read on section filter
ERROR error while reading the NIT table
dvb_read_sections: waiting for table ID 0x42, program ID 0x11
dvb_parse_section: received table 0x42, extension ID 0x0744, section 0/0
dvb_parse_section: table 0x42, extension ID 0x0744: done
SDT
| table_id 0x42
| section_length 48
| one 2
| zero 1
| syntax 1
| transport_stream_id 1860
| current_next 1
| version 1
| one2 3
| section_number 0
| last_section_number 0
| network_id 1860
| reserved 255
|\
|- service 0x0880
| EIT schedule 0
| EIT present following 0
| free CA mode 0
| running status 4
| descriptor length 31
| 0x48: service_descriptor
| service type 1
| provider '(null)'
| name 'S302m: Sine Wave PCM Audio'
|_ 1 services
Service S302m: Sine Wave PCM Audio, provider (null): digital television
Storing as channel S302m: Sine Wave PCM Audio

$ dvbv5-zap -c dvb_channel.conf "S302m: Sine Wave PCM Audio" -m
...
PID FREQ SPEED TOTAL
0 25.07 p/s 36.826 Kbps 55 KB
17 25.07 p/s 36.826 Kbps 55 KB
257 25.07 p/s 36.826 Kbps 55 KB
273 1335.19 p/s 1.915 Mbps 2943 KB
512 25.07 p/s 36.826 Kbps 55 KB
8191 16775.59 p/s 24.062 Mbps 36974 KB
TOT 18211.08 p/s 26.121 Mbps 40138 KB

Lock (0x1f) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0


$ dvbv5-zap -c dvb_channel.conf "S302m: Sine Wave PCM Audio" -t 30 -o pcm_audio.ts
using demux 'dvb0.demux0'
reading channels from file 'dvb_channel.conf'
service has pid type 06: 273
tuning to 330000000 Hz
(0x00) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0
Lock (0x1f) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0
Lock (0x1f) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0
Record to file 'pcm_audio.ts' started
Forcing program stop due to timeout or terminate signal

$ ls -l pcm_audio.ts
-rw-r--r-- 1 mchehab mchehab 0 Sep 11 09:46 pcm_audio.ts

$ dvbv5-zap -c dvb_channel.conf "S302m: Sine Wave PCM Audio" -t 30 -o pcm_audio.ts -P
using demux 'dvb0.demux0'
reading channels from file 'dvb_channel.conf'
service has pid type 06: 273
tuning to 330000000 Hz
pass all PID's to TS
dvb_set_pesfilter 8192
dvb_dev_set_bufsize: buffer set to 6160384
Lock (0x1f) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0
Lock (0x1f) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0
Record to file 'pcm_audio.ts' started
received 103809840 bytes (3379 Kbytes/sec)
Lock (0x1f) Signal= 0.00% C/N= 0.00% UCB= 0 postBER= 0

$ ls -lh pcm_audio.ts
-rw-r--r-- 1 mchehab mchehab 100M Sep 11 09:54 pcm_audio.ts


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