mpegts issue on localhost

[burek]

Hi,

In response to https://ffmpeg.org/trac/ffmpeg/ticket/602 (cehoyos), I'll try to provide my experience with mpegts format.

Here is the first issue. I have 2 ffmpeg processes, the first one should send the a/v (aac+h264) to the localhost:port using udp, and the 2nd ffmpeg process should pick it up and just save to the .ts file.

This is the command line of the first ffmpeg:

ffmpeg -y -re \
        -f video4linux2 -r 30 -s qvga -i /dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0 \
        -f alsa -ar 44100 -ac 2 -i default:CARD=Intel \
        -vcodec libx264 -crf 20 -threads 0 \
        -acodec aac -ab 32k -ar 44100 -ac 2 \
        -strict experimental \
        -vbsf h264_mp4toannexb \
        -absf aac_adtstoasc \
        -f mpegts udp://127.0.0.1:10001

And this is the command of the 2nd ffmpeg:

ffmpeg -muxdelay 15 -f mpegts -i udp://localhost:10001 -acodec copy -vcodec copy out.ts

Now, when I try to play the .ts file in VLC, I can watch the video, but in the message log I can see a lot of those:

main warning: late picture skipped (35805 > -268)
main warning: late picture skipped (2472 > -268)
main warning: late picture skipped (7218 > -262)
main warning: late picture skipped (1171 > -334)
main warning: late picture skipped (24818 > -266)
main warning: late picture skipped (19257 > -277)
main warning: late picture skipped (14977 > -303)
main warning: late picture skipped (57074 > -266)
main warning: late picture skipped (23740 > -266)
main warning: late picture skipped (5374 > -265)
main warning: late picture skipped (1929 > -15969)
main warning: late picture skipped (1376 > -264)

I'm sure the network is not an issue here :) and also, I've monitored cpu usage (on a dual core) and it didn't go over 40% at any time.

Also, when I record a live stream this way for a very long time (like 12 hours or more) the audio and video get totally async, meaning audio is progressively advancing before the video and after like 3-4 hours of recording, the drift is around 10 seconds and will get even bigger for the longer period of the recording.

I can send you samples of .ts files, only I'll need to record for that long, so you can see that it really happens.

Other issues are related to remuxing from .ts to .flv (also with h264+aac), but I'll see to create new tickets for that.

[Carl Eugen Hoyos]

Assuming this is not reproducible with

ffmpeg -re -f video4linux2 -r 30 -s qvga -i /dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0 -vcodec libx264 -crf 20 -vbsf h264_mp4toannexb out.ts

Isn't this more an udp issue?

And why are you using the bsf?

[burek]

Well, I didn't try just recording to .ts file for that long, more rational way was to stream to an udp port because that way I could duplicate the data and watch it, while it is being saved to a file.

Anyway, for the absf, I don't remember now where exactly did I pick up that option (was it in ffmpeg channel or google), I just know that without it, when I play the udp stream in VLC, then the audio is a lot more quirky, skipping up/down-sampling and stuff... And since there is no official documentation on that filter ( ​http://ffmpeg.org/ffmpeg.html#aac_005fadtstoasc ), I didn't have chance to read about its real intended usage, so it might be the reason of the async behavior.

Can You give me one working example (default or something) of using mpegts (h264+aac) over udp, just to test it, because I've tried so many different combinations and variations I can't even remember now and none of them gave the smooth and clean playback without async (I'm talking about 100/100 LAN network). What could be the simplest way to start such a stream?

[Carl Eugen Hoyos]

I meant the video bitstream filter that should only make sense when stream copying from mp4.

To clarify:
Does creating the transport stream without using udp (and without audio and without the video bitstream filter) produce a file that does not show the warnings in vlc?

[burek]

why without audio?

and yes, it does:

ffmpeg:

ffmpeg -y -re \
        -f video4linux2 -r 30 -s qvga -i /dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0 \
        -vcodec libx264 -crf 20 -threads 0 \
        out.ts

vlc:

main debug: processing request item out.ts node Playlist skip 0
main debug: resyncing on out.ts
main debug: out.ts is at 0
main debug: starting new item
main debug: creating new input thread
main debug: Creating an input for 'out.ts'
main debug: thread (input) created at priority 1 (../.././src/input/input.c:220)
qt4 debug: IM: Setting an input
main debug: thread started
main debug: using timeshift granularity of 50 MiB
main debug: using timeshift path 'C:\DOCUME~1\YourUsernameHere\LOCALS~1\Temp'
main debug: `file:///C:/Documents%20and%20Settings/YourUsernameHere/Desktop/out.ts' gives access `file' demux `' path `C:\Documents and Settings\YourUsernameHere\Desktop\out.ts'
main debug: creating demux: access='file' demux='' path='C:\Documents and Settings\YourUsernameHere\Desktop\out.ts'
main debug: looking for access_demux module: 2 candidates
main debug: no access_demux module matching "file" could be loaded
main debug: TIMER module_need() : 38.501 ms - Total 38.501 ms / 1 intvls (Avg 38.501 ms)
main debug: creating access 'file' path='C:\Documents and Settings\YourUsernameHere\Desktop\out.ts'
main debug: looking for access module: 2 candidates
filesystem debug: opening file `C:\Documents and Settings\YourUsernameHere\Desktop\out.ts'
main debug: using access module "filesystem"
main debug: TIMER module_need() : 36.555 ms - Total 36.555 ms / 1 intvls (Avg 36.555 ms)
main debug: Using AStream*Stream
main debug: pre buffering
main debug: received first data after 0 ms
main debug: pre-buffering done 1024 bytes in 0s - 6060 KiB/s
main debug: looking for stream_filter module: 2 candidates
main debug: no stream_filter module matching "any" could be loaded
main debug: TIMER module_need() : 0.427 ms - Total 0.427 ms / 1 intvls (Avg 0.427 ms)
main debug: looking for stream_filter module: 1 candidate
main debug: using stream_filter module "stream_filter_record"
main debug: TIMER module_need() : 0.412 ms - Total 0.412 ms / 1 intvls (Avg 0.412 ms)
main debug: creating demux: access='file' demux='' path='C:\Documents and Settings\YourUsernameHere\Desktop\out.ts'
main debug: looking for demux module: 52 candidates
ts debug: PATCallBack called
ts debug: new PAT ts_id=1 version=0 current_next=1
ts debug:   * number=1 pid=4096
ts debug: PMTCallBack called
ts debug: new PMT program number=1 version=0 pid_pcr=256
ts debug:   * es pid=256 type=27 fcc=h264
main debug: selecting program id=1
filesystem warning: unimplemented query 4097 in control
main debug: using demux module "ts"
main debug: TIMER module_need() : 2.874 ms - Total 2.874 ms / 1 intvls (Avg 2.874 ms)
main debug: looking for a subtitle file in C:\Documents and Settings\YourUsernameHere\Desktop\
main debug: looking for decoder module: 34 candidates
avcodec debug: libavcodec already initialized
avcodec debug: trying to use direct rendering
avcodec debug: ffmpeg codec (H264 - MPEG-4 AVC (part 10)) started
main debug: using decoder module "avcodec"
main debug: TIMER module_need() : 2.785 ms - Total 2.785 ms / 1 intvls (Avg 2.785 ms)
main debug: looking for packetizer module: 21 candidates
main debug: using packetizer module "packetizer_h264"
main debug: TIMER module_need() : 0.528 ms - Total 0.528 ms / 1 intvls (Avg 0.528 ms)
main debug: thread (decoder) created at priority 0 (../.././src/input/decoder.c:301)
main debug: thread started
ts debug: DEMUX_SET_GROUP 0 00000000
main debug: looking for meta reader module: 2 candidates
lua debug: Trying Lua scripts in C:\Documents and Settings\YourUsernameHere\Application Data\vlc\lua\meta\reader
lua debug: Trying Lua scripts in C:\Program Files\VideoLAN\VLC\lua\meta\reader
lua debug: Trying Lua playlist script C:\Program Files\VideoLAN\VLC\lua\meta\reader\filename.lua
main debug: no meta reader module matching "any" could be loaded
main debug: TIMER module_need() : 38.648 ms - Total 38.648 ms / 1 intvls (Avg 38.648 ms)
main debug: `file:///C:/Documents%20and%20Settings/YourUsernameHere/Desktop/out.ts' successfully opened
main debug: Buffering 0%
main debug: Buffering 33%
main debug: Buffering 66%
main debug: Buffering 100%
main debug: Stream buffering done (400 ms in 39 ms)
packetizer_h264 debug: found NAL_SPS (sps_id=0)
packetizer_h264 debug: found NAL_PPS (pps_id=0 sps_id=0)
main debug: no usable vout present, spawning one
main debug: looking for text renderer module: 2 candidates
freetype debug: Using Arial as font from file C:\WINDOWS\Fonts\ARIAL.TTF
freetype debug: using fontsize: 2
main debug: using text renderer module "freetype"
main debug: TIMER module_need() : 28.828 ms - Total 28.828 ms / 1 intvls (Avg 28.828 ms)
main debug: looking for video filter2 module: 18 candidates
swscale debug: 32x32 chroma: YUVA -> 16x16 chroma: YUVA with scaling using Bicubic (good quality)
main debug: using video filter2 module "swscale"
main debug: TIMER module_need() : 22.706 ms - Total 22.706 ms / 1 intvls (Avg 22.706 ms)
main debug: looking for video filter2 module: 18 candidates
yuvp debug: YUVP to YUVA converter
main debug: using video filter2 module "yuvp"
main debug: TIMER module_need() : 128.555 ms - Total 128.555 ms / 1 intvls (Avg 128.555 ms)
main debug: window size: 320x240
main debug: Deinterlacing available
main debug: deinterlace 0, mode blend, is_needed 0
main debug: looking for video output module: 1 candidate
vout_wrapper debug: Opening vout display wrapper
main debug: looking for vout display module: 8 candidates
directx debug: creating Vout EventThread
directx debug: DirectXCreateWindow
main debug: looking for vout window hwnd module: 3 candidates
qt4 debug: requesting video...
qt4 debug: Video was requested 0, 0
main debug: using vout window hwnd module "qt4"
main debug: TIMER module_need() : 35.024 ms - Total 35.024 ms / 1 intvls (Avg 35.024 ms)
directx debug: created video sub-window
directx debug: Vout EventThread running
directx debug: disabling screen saver
directx debug: directx-device: 
directx debug: DirectXEnumCallback: RADEON 9250, \\.\DISPLAY1
directx debug: selecting RADEON 9250, \\.\DISPLAY1
directx debug: screen dimensions (0x0,1280x768)
directx debug: DirectDraw Capabilities: overlay=1 yuvoverlay=1 can_deinterlace_overlay=1 colorkey=1 stretch=1 bltfourcc=1
main debug: VoutDisplayEvent 'resize' 328x274 window
directx debug: YUV overlay surface created successfully
main debug: using vout display module "directx"
main debug: TIMER module_need() : 163.982 ms - Total 163.982 ms / 1 intvls (Avg 163.982 ms)
main debug: using video output module "vout_wrapper"
main debug: TIMER module_need() : 192.057 ms - Total 192.057 ms / 1 intvls (Avg 192.057 ms)
main debug: got 1 direct buffer(s)
main debug: pic render sz 320x240, of (0,0), vsz 320x240, 4cc I420, sar 1:1, msk r0x0 g0x0 b0x0
main debug: pic in sz 320x240, of (0,0), vsz 320x240, 4cc I420, sar 1:1, msk r0x0 g0x0 b0x0
main debug: pic out sz 320x240, of (0,0), vsz 320x240, 4cc I420, sar 1:1, msk r0x0 g0x0 b0x0
main debug: direct render, mapping render pictures 0-23 to system pictures 1-24
avcodec debug: using direct rendering
main debug: VoutDisplayEvent 'resize' 427x240 window
main debug: End of video preroll
main debug: Received first picture
main debug: Decoder buffering done in 546 ms
main debug: Post-processing available
main warning: vlc_object_find_name(postproc) is not safe!
freetype debug: using fontsize: 15
main debug: looking for video blending module: 1 candidate
blend debug: chroma: YUVA -> I420
main debug: using video blending module "blend"
main debug: TIMER module_need() : 33.145 ms - Total 33.145 ms / 1 intvls (Avg 33.145 ms)
main debug: auto hidding mouse
ts debug: PSINewTableCallBack: table 0x42(66) ext=0x1(1)
ts debug: SDTCallBack called
ts debug: new SDT ts_id=1 version=0 current_next=1 network_id=1
ts debug:   * service id=1 eit schedule=0 present=0 running=4 free_ca=0
ts debug:     - type=1 provider=FFmpeg name=Service01
main debug: EsOutProgramMeta: number=1
main warning: late picture skipped (21217 > -396)
main warning: late picture skipped (54550 > -396)
main warning: late picture skipped (16039 > -387)
main warning: late picture skipped (5155 > -398)
main warning: late picture skipped (9904 > -252)
main warning: late picture skipped (25470 > -262)
main warning: late picture skipped (33866 > -261)
main warning: late picture skipped (533 > -261)
main warning: late picture skipped (10743 > -260)
main warning: late picture skipped (11036 > -261)
main warning: late picture skipped (10930 > -262)
main warning: late picture skipped (6950 > -258)
main warning: late picture skipped (3569 > -258)
main warning: late picture skipped (33738 > -261)
main warning: late picture skipped (404 > -261)
main warning: late picture skipped (10463 > -258)
main warning: late picture skipped (6305 > -268)
main warning: late picture skipped (11728 > -253)
ts debug: eof ?
main debug: EOF reached

[burek]

encoding audio only works just fine:

ffmpeg -y -re \
        -f alsa -ar 44100 -ac 2 -i default:CARD=Intel \
        -acodec aac -ab 32k -ar 44100 -ac 2 \
        -strict experimental \
        out.ts

No warnings, errors, nothin, just clear audio :)

[Carl Eugen Hoyos]

Is this only reproducible with an external library (-vcodec libx264) or also with an internal encoder?

Please post complete, uncut console output (including command line) without -threads 0.

And do you have any idea what the vlc warnings mean? Are there any visible problems with the resulting file? Do other players (ffplay, MPlayer, WMP 12) show any problems?

[burek]

Same scenario with this example (mpeg2video):

ffmpeg -y -re \
        -f video4linux2 -r 30 -s qvga -i /dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0 \
        out.ts

ffmpeg version N-34519-g54a09f1, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov  6 2011 12:46:05 with gcc 4.6.1
  configuration: --enable-static --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-libx264 --enable-libaacplus --enable-libmp3lame --enable-libv4l2 --enable-libvo-aacenc --enable-version3
  libavutil    51. 23. 0 / 51. 23. 0
  libavcodec   53. 28. 0 / 53. 28. 0
  libavformat  53. 19. 0 / 53. 19. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 47. 0 /  2. 47. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[video4linux2,v4l2 @ 0x1f9c980] Estimating duration from bitrate, this may be inaccurate
Input #0, video4linux2,v4l2, from '/dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0':
  Duration: N/A, start: 27501.143731, bitrate: 27648 kb/s
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 320x240, 27648 kb/s, 30 tbr, 1000k tbn, 30 tbc
[buffer @ 0x1f9c800] w:320 h:240 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param:
[mpegts @ 0x1f97040] muxrate VBR, pcr every 3 pkts, sdt every 200, pat/pmt every 40 pkts
Output #0, mpegts, to 'out.ts':
  Metadata:
    encoder         : Lavf53.19.0
    Stream #0:0: Video: mpeg2video, yuv420p, 320x240, q=2-31, 200 kb/s, 90k tbn, 30 tbc
Stream mapping:
  Stream #0.0 -> #0.0 (rawvideo -> mpeg2video)
Press [q] to stop, [?] for help
frame=  976 fps= 30 q=5.7 Lsize=    1257kB time=00:00:32.50 bitrate= 317.0kbits/s dup=638 drop=0
video:1070kB audio:0kB global headers:0kB muxing overhead 17.558359%

And here is libx264 without -threads:

# ffmpeg -y -re \
        -f video4linux2 -r 30 -s qvga -i /dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0 \
        -vcodec libx264 -crf 20 \
        out.ts

ffmpeg version N-34519-g54a09f1, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov  6 2011 12:46:05 with gcc 4.6.1
  configuration: --enable-static --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-libx264 --enable-libaacplus --enable-libmp3lame --enable-libv4l2 --enable-libvo-aacenc --enable-version3
  libavutil    51. 23. 0 / 51. 23. 0
  libavcodec   53. 28. 0 / 53. 28. 0
  libavformat  53. 19. 0 / 53. 19. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 47. 0 /  2. 47. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[video4linux2,v4l2 @ 0x707980] Estimating duration from bitrate, this may be inaccurate
Input #0, video4linux2,v4l2, from '/dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0':
  Duration: N/A, start: 27685.969253, bitrate: 27648 kb/s
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 320x240, 27648 kb/s, 30 tbr, 1000k tbn, 30 tbc
[buffer @ 0x708440] w:320 h:240 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param:
[libx264 @ 0x7025a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64
[libx264 @ 0x7025a0] profile High, level 1.3
[mpegts @ 0x702040] muxrate VBR, pcr every 3 pkts, sdt every 200, pat/pmt every 40 pkts
Output #0, mpegts, to 'out.ts':
  Metadata:
    encoder         : Lavf53.19.0
    Stream #0:0: Video: h264, yuv420p, 320x240, q=-1--1, 90k tbn, 30 tbc
Stream mapping:
  Stream #0.0 -> #0.0 (rawvideo -> libx264)
Press [q] to stop, [?] for help
frame=  636 fps= 29 q=-1.0 Lsize=     626kB time=00:00:21.13 bitrate= 242.5kbits/s dup=442 drop=0
video:497kB audio:0kB global headers:0kB muxing overhead 25.792506%
[libx264 @ 0x7025a0] frame I:3     Avg QP:14.98  size: 15692
[libx264 @ 0x7025a0] frame P:424   Avg QP:19.03  size:  1074
[libx264 @ 0x7025a0] frame B:209   Avg QP:25.71  size:    33
[libx264 @ 0x7025a0] consecutive B-frames: 56.1%  0.0%  0.5% 43.4%
[libx264 @ 0x7025a0] mb I  I16..4:  2.4% 62.2% 35.3%
[libx264 @ 0x7025a0] mb P  I16..4:  0.0%  0.1%  0.0%  P16..4: 33.9%  9.4%  7.7%  0.0%  0.0%    skip:48.9%
[libx264 @ 0x7025a0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  3.4%  0.0%  0.0%  direct: 0.2%  skip:96.3%  L0:54.6% L1:44.0% BI: 1.4%
[libx264 @ 0x7025a0] 8x8 transform intra:64.4% inter:74.7%
[libx264 @ 0x7025a0] coded y,uvDC,uvAC intra: 97.3% 99.6% 98.7% inter: 9.6% 30.5% 18.6%
[libx264 @ 0x7025a0] i16 v,h,dc,p:  3%  3% 29% 65%
[libx264 @ 0x7025a0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 18% 20% 13%  3%  9%  5% 17%  5%  9%
[libx264 @ 0x7025a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 18% 20%  8%  5% 10%  6% 15%  9%  9%
[libx264 @ 0x7025a0] i8c dc,h,v,p: 62% 19% 10%  9%
[libx264 @ 0x7025a0] Weighted P-Frames: Y:0.7% UV:0.2%
[libx264 @ 0x7025a0] ref P L0: 63.4%  6.8%  7.9% 21.7%  0.1%
[libx264 @ 0x7025a0] ref B L0: 85.1% 13.1%  1.8%
[libx264 @ 0x7025a0] ref B L1: 91.4%  8.6%
[libx264 @ 0x7025a0] kb/s:192.20

The problem still exists.
That message tells that the timestamps are somehow wrong, I guess. Sometimes I can see the image freezes for a fraction of a second and the image goes distorted just like a wrong keyframe was used for all the subsequent delta frames, but it gets back to normal after a couple of seconds.

[Carl Eugen Hoyos]

Are the problems only reproducible with -vcodec mpeg2video -f mpegts or also for -vcodec mpeg2video -f avi/mpg/mkv ?

[burek]

-vcodec mpeg2video -f avi: no warnings at all
-vcodec mpeg2video -f mpeg: warnings are there constantly, just like with mpegts
-vcodec mpeg2video -f matroska: no warnings at all

[Carl Eugen Hoyos]

Is the problem also reproducible with

ffmpeg -f video4linux2 -i /dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0 out.ts

?
Or is -r 30 needed to make the conversion work at all?

[burek]

-r 30 just tells the driver to correctly sample the video input, so we don't have to resample it afterwards

here is the log:

# ffmpeg -f video4linux2 -i /dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0 out.ts
ffmpeg version N-34519-g54a09f1, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov  6 2011 12:46:05 with gcc 4.6.1
  configuration: --enable-static --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-libx264 --enab                                     le-libaacplus --enable-libmp3lame --enable-libv4l2 --enable-libvo-aacenc --enable-version3
  libavutil    51. 23. 0 / 51. 23. 0
  libavcodec   53. 28. 0 / 53. 28. 0
  libavformat  53. 19. 0 / 53. 19. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 47. 0 /  2. 47. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[video4linux2,v4l2 @ 0x1daf780] The driver changed the time per frame from 32767/1996117544 to 1/30
[video4linux2,v4l2 @ 0x1daf780] Estimating duration from bitrate, this may be inaccurate
Input #0, video4linux2,v4l2, from '/dev/v4l/by-id/usb-046d_0809_33A881A3-video-index0':
  Duration: N/A, start: 25528.008073, bitrate: 27648 kb/s
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 320x240, 27648 kb/s, 30 tbr, 1000k tbn, 30 tbc
[buffer @ 0x1dbdf40] w:320 h:240 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param:
[mpegts @ 0x1dbd0a0] muxrate VBR, pcr every 3 pkts, sdt every 200, pat/pmt every 40 pkts
Output #0, mpegts, to 'out.ts':
  Metadata:
    encoder         : Lavf53.19.0
    Stream #0:0: Video: mpeg2video, yuv420p, 320x240, q=2-31, 200 kb/s, 90k tbn, 30 tbc
Stream mapping:
  Stream #0.0 -> #0.0 (rawvideo -> mpeg2video)
Press [q] to stop, [?] for help
frame=  480 fps= 37 q=10.3 Lsize=     754kB time=00:00:15.96 bitrate= 386.9kbits/s dup=287 drop=0
video:658kB audio:0kB global headers:0kB muxing overhead 14.622744%

and warnings are also there again :/

[burek]

I apologize, it seems that this error is related to a slow hardware (??) although I'm not sure why, because the cpu usage never gets over 30-40%, but they say its related to a slow decoder/cpu or something like that, so this bug report can be closed without further examination, I guess.