[mythtv-users] IPTV recorder seems broken -- large jumpy files

Mark Perkins perkins1724 at hotmail.com
Sat Mar 17 22:58:49 UTC 2018



On 18/03/18 08:41, Mark Perkins wrote:
>
> On 03/03/18 23:32, Brian J. Murrell wrote:
>> I have been trying to use the IPTV recorder to record from a particular
>> HLS stream.
>>
>> The files resulting from this recording are on the order of 10GB per
>> hour, which is ridiculous.  They also "jump" around while trying to
>> play them, even with something as generic as mplayer.
>>
>> I have used "ffmpeg -acodec copy -vcodec copy" to record from the exact
>> same m3u8 that I am giving to the IPTV recorder and I get something
>> more reasonably on the order of 1GB per hour and perfectly playable.
>>
>> I wonder if anyone else has experienced anything similar.
>>
>> I wonder if anyone has written an "external recorder" around ffmpeg as
>> a stream copier that they want to share as an alternative to the IPTV
>> recorder.
>>
>> Cheers,
>> b.
>>
> Have you tried using ffmpeg -i or mediainfo or something equivalent to
> compare the file created by mythtv to the file created from ffmpeg? I
> would be curious to know what was in the big file that was making it so big.
> _______________________________________________
>
Just to put some additional words around this. I use the IPTV recorder 
functionality for my recordings. I have a box with USB DVB-T tuners 
attached that runs mumudvb to rebroadcast the streams to multicast IP. I 
can then subscribe to those streams from as many mythbackends as I like 
simultaneously from anywhere on my network. I picked a SD recording from 
the news last night which was 588MiB for 27min which is fairly 
comparable to your 1GB per hour. So I don't think your large file sizes 
are necessarily a problem with the IPTV recorder functionality but 
perhaps related to what is specifically being transmitted in the stream. 
Although I have no immediate suggestions as to what the IPTV recorder 
functionality is including that is quite large in size but is excluded 
by "ffmpeg -acodec copy -vcodec copy".

If I had to guess, based on your sizes, perhaps the IPTV recorder has 
recorded an entire multiplex not just a specific channel / stream? 
Mediainfo or ffmpeg on the file should reveal more.

Here are some stats from my news recording:

$ ls -alh 1002_20180317093300.ts
-rw-rw-r--. 1 mythtv mythtv 562M Mar 17 20:30 1002_20180317093300.ts

$ ffmpeg -i 1002_20180317093300.ts
ffmpeg version N-90289-g8fb0e51 Copyright (c) 2000-2018 the FFmpeg 
developers
   built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-16)
   configuration: --prefix=/root/ffmpeg_build 
--pkg-config-flags=--static --extra-cflags=-I/root/ffmpeg_build/include 
--extra-ldflags=-L/root/ffmpeg_build/lib --extra-libs='-lm -lpthread' 
--bindir=/usr/local/bin --enable-gpl --enable-libfdk_aac 
--enable-libfreetype --enable-libmp3lame --enable-libopus 
--enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
   libavutil      56.  9.100 / 56.  9.100
   libavcodec     58. 14.100 / 58. 14.100
   libavformat    58. 10.100 / 58. 10.100
   libavdevice    58.  2.100 / 58.  2.100
   libavfilter     7. 13.100 /  7. 13.100
   libswscale      5.  0.102 /  5.  0.102
   libswresample   3.  0.101 /  3.  0.101
   libpostproc    55.  0.100 / 55.  0.100
[mp3 @ 0x3f69840] Header missing
[mpegts @ 0x3f63980] PES packet size mismatch
[mpegts @ 0x3f63980] Could not find codec parameters for stream 3 
(Unknown: none ([11][0][0][0] / 0x000B)): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' 
options
[mpegts @ 0x3f63980] Could not find codec parameters for stream 4 
(Unknown: none ([5][0][0][0] / 0x0005)): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' 
options
Input #0, mpegts, from '1002_20180317093300.ts':
   Duration: 00:27:02.82, start: 9533.651444, bitrate: 2900 kb/s
   Program 1
     Stream #0:0[0x200]: Video: mpeg2video (Main) ([2][0][0][0] / 
0x0002), yuv420p(tv, bt470bg, top first), 720x576 [SAR 64:45 DAR 16:9], 
25 fps, 25 tbr, 90k tbn, 50 tbc
     Stream #0:1[0x28a]: Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, 
stereo, s16p, 256 kb/s
     Stream #0:2[0x240](eng): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
     Stream #0:3[0x157d]: Unknown: none ([11][0][0][0] / 0x000B)
     Stream #0:4[0x157c]: Unknown: none ([5][0][0][0] / 0x0005)
At least one output file must be specified


$ mediainfo 1002_20180317093300.ts
General
ID                                       : 593 (0x251)
Complete name                            : 1002_20180317093300.ts
Format                                   : MPEG-TS
File size                                : 561 MiB
Duration                                 : 27 min 2 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 2 901 kb/s

Video
ID                                       : 512 (0x200)
Menu ID                                  : 1 (0x1)
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : Main at Main
Format settings                          : CustomMatrix / BVOP
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Custom
Format settings, GOP                     : Variable
Format settings, picture structure       : Frame
Codec ID                                 : 2
Duration                                 : 27 min 2 s
Bit rate mode                            : Variable
Bit rate                                 : 2 499 kb/s
Maximum bit rate                         : 6 000 kb/s
Width                                    : 720 pixels
Height                                   : 576 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 25.000 FPS
Standard                                 : PAL
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Interlaced
Scan order                               : Top Field First
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.241
Stream size                              : 483 MiB (86%)
Writing library                          : xec 7.1.18
Color primaries                          : BT.601 PAL
Transfer characteristics                 : BT.470 System B, BT.470 System G
Matrix coefficients                      : BT.470 System B, BT.470 System G

Audio
ID                                       : 650 (0x28A)
Menu ID                                  : 1 (0x1)
Format                                   : MPEG Audio
Format version                           : Version 1
Format profile                           : Layer 2
Codec ID                                 : 3
Duration                                 : 27 min 2 s
Bit rate mode                            : Constant
Bit rate                                 : 256 kb/s
Maximum bit rate                         : 272 kb/s
Channel(s)                               : 2 channels
Sampling rate                            : 48.0 kHz
Frame rate                               : 41.667 FPS (1152 SPF)
Compression mode                         : Lossy
Delay relative to video                  : -419 ms
Stream size                              : 49.5 MiB (9%)

Text
ID                                       : 576 (0x240)-801
Menu ID                                  : 1 (0x1)
Format                                   : Teletext Subtitle
Language                                 : English

Menu
ID                                       : 256 (0x100)
Menu ID                                  : 1 (0x1)
List                                     : 512 (0x200) (MPEG Video) / 
650 (0x28A) (MPEG Audio) / 576 (0x240)-801 (Teletext Subtitle, en)
Language                                 :  /  / English
Maximum bit rate                         : 6726000




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