interlacing problem

[mitja]

Hi,

I am experiencing a interlacing effect on DVB-T grabbed streams. In fast moving scenes or between news when text scrolls it is barely readable. First I thought it is ffmpeg related then mumudvb, but actually it could be hardware/driver related. It happens on all streams and on both tuners. I use mumudvb do grab DVB-T streams and send them to multicast.

Any idea why is it happening?
These "interlaced effect" I get when watching a grabbed DVB-T multicast stream on laptop (VLC) and on android IPTV with XBMC on a regular TV set (Samsung 42"). Could it be resolution related? IPTV STB connects full HD with the TV set while the grabbed stream is at 720x576?

Input stream:

ffprobe -i udp://239.100.0.0:1234
Input #0, mpegts, from 'udp://239.100.0.0:1234':
Duration: N/A, start: 77357.106233, bitrate: 192 kb/s
Program 1
Metadata:
service_name : SLO1
service_provider: RTV SLOVENIJA
Stream #0:0[0x78]: Video: h264 (Main) ([27][0][0][0] / 0x001B),
yuv420p(tv, bt470bg), 720x576 [SAR 16:11 DAR 20:11], 25 fps, 50 tbr, 90k
tbn, 50 tbc
Stream #0:1[0x79](slv): Audio: mp2 ([4][0][0][0] / 0x0004), 48000
Hz, stereo, s16p, 192 kb/s
Stream #0:2[0x7a](slv): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
Stream #0:3[0x7b]: Audio: mp1 ([6][0][0][0] / 0x0006), 0 channels,
s16p
Unsupported codec with id 94215 for input stream 2
[STREAM]
index=0
codec_name=h264
codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
profile=Main
codec_type=video
codec_time_base=1/50
codec_tag_string=[27][0][0][0]
codec_tag=0x001b
width=720
height=576
has_b_frames=2
sample_aspect_ratio=16:11
display_aspect_ratio=20:11
pix_fmt=yuv420p
level=30
timecode=N/A
id=0x78
r_frame_rate=50/1
avg_frame_rate=25/1
time_base=1/90000
start_pts=6962200658
start_time=77357.785089
duration_ts=N/A
duration=N/A
bit_rate=N/A
nb_frames=N/A
nb_read_frames=N/A
nb_read_packets=N/A
extradata=
00000000: 0000 0001 0910 0000 0001 274d 401e 9a62 ..........'M@..b
00000010: 0168 48b0 4420 a0a0 a800 0003 0008 0000 .hH.D ..........
00000020: 0301 94a0 0000 0001 28ee 3c80 ........(.<.

DISPOSITION:default=0
DISPOSITION:dub=0
DISPOSITION:original=0
DISPOSITION:comment=0
DISPOSITION:lyrics=0
DISPOSITION:karaoke=0
DISPOSITION:forced=0
DISPOSITION:hearing_impaired=0
DISPOSITION:visual_impaired=0
DISPOSITION:clean_effects=0
DISPOSITION:attached_pic=0
[/STREAM]

Hardware:
TBS 5280
IBM x3650 2x quadcore X5365 @ 3.00GHz, 24GB RAM

Software:
#lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 13.10
Release: 13.10
Codename: saucy

#uname -a
Linux IPTV 3.11.0-12-generic #19-Ubuntu SMP Wed Oct 9 16:20:46 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

# dmesg | grep video
[ 0.329664] pci 0000:01:06.0: Boot video device
[ 19.720935] Linux video capture interface: v2.00
[ 21.936989] cx231xx #0: cx231xx #0/0: registered device video0 [v4l2]
[ 21.937047] cx231xx #0: V4L2 device registered as video0 and vbi0

# lsmod
Module Size Used by
tbs5280fe 18969 2
cx231xx_dvb 18126 60
dvb_core 109805 1 cx231xx_dvb
cx231xx_alsa 17866 0
snd_pcm 102033 1 cx231xx_alsa
snd_page_alloc 18710 1 snd_pcm
snd_timer 29433 1 snd_pcm
snd 69141 3 cx231xx_alsa,snd_timer,snd_pcm
soundcore 12680 1 snd
cx25840 53326 1
ext2 72832 1
coretemp 13435 0
kvm_intel 138538 0
kvm 431315 1 kvm_intel
gpio_ich 13476 0
lpc_ich 21080 0
cx231xx 177864 2 cx231xx_alsa,cx231xx_dvb
videobuf_vmalloc 13560 1 cx231xx
cx2341x 28230 1 cx231xx
videobuf_core 25993 2 cx231xx,videobuf_vmalloc
v4l2_common 16391 3 cx2341x,cx231xx,cx25840
videodev 97653 4 cx2341x,cx231xx,cx25840,v4l2_common
v4l2_compat_ioctl32 16692 1 videodev
ibmpex 13193 0
ibmaem 17838 0
ipmi_msghandler 45306 2 ibmaem,ibmpex
ics932s401 13824 0
radeon 1402449 1
microcode 23518 0
ir_lirc_codec 12898 0
lirc_dev 19166 1 ir_lirc_codec
psmouse 97626 0
serio_raw 13413 0
ir_mce_kbd_decoder 12845 0
ir_sony_decoder 12549 0
rc_tbs_nec 12502 0
joydev 17377 0
ir_jvc_decoder 12546 0
ttm 83995 1 radeon
ir_rc6_decoder 12546 0
ir_rc5_decoder 12546 0
drm_kms_helper 52651 1 radeon
ir_nec_decoder 12546 0
mceusb 17693 0
drm 296739 3 ttm,drm_kms_helper,radeon
rc_core 26854 11 cx231xx,ir_lirc_codec,ir_rc5_decoder,ir_nec_decoder,ir_sony_decoder,rc_tbs_nec,mceusb,ir_mce_kbd_decoder,ir_jvc_decoder,ir_rc6_decoder
i2c_algo_bit 13413 1 radeon
i5000_edac 17405 0
edac_core 62312 2 i5000_edac
ioatdma 67292 6
i5k_amb 13146 0
dca 15130 1 ioatdma
shpchp 37032 0
mac_hid 13205 0
lp 17759 0
parport 42299 1 lp
ses 17363 0
enclosure 15179 1 ses
hid_generic 12548 0
usbhid 53014 0
hid 101512 2 hid_generic,usbhid
bnx2 84643 0
aacraid 95456 2

[cody]

Hi, it's not neither hardware, nor driver related, because neither DVB drivers, nor DVB hardware process the data in any way. so, DVB hardware and drivers are like your WiFi cards and drivers for Internet connection with the only difference they download digital TV data from the air. in other words those digital TV data as received are sent to video codecs and rest of your hardware (CPU, graphic card) for processing. my best guess is that de-interlacing is just not enabled in the software you use for watching.

[mitja]

Thank you cody for your post.

For future reference I am posting an answer from mumudvb forum (thanks to Matthias Šubik):
The format the content was shot in is called SD-TV, which is by definition interlaced. This is how analog tv was invented, to save bandwidth, and to get the picture moving. Now it is a legacy, as technical constrains, CRTs, and tape machines for video recording all all gone. All modern TV sets should have a good interlacing filter, as it needs it for most (pure SD) TV stations that still provide interlaced material.

Mitja