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• GStreamer with MPEG-TS Video4Linux ATSC/DVB Recording

  21 juin 2013, par Dustin Oprea

  I'm having an impossible time setting up a filtergraph to read from a recording that I made from my DVB video4linux device. Any help would be vastly appreciated.

  How I made the recording :

  To tune the channel :

  azap -c ~/channels.conf "Florida"

  To record the channel :

  cat /dev/dvb/adapter0/dvr0 > /tmp/test

  This is the way that recordings must be made (I can not use any GST DVB plugins to do this for me).

  I used tstools to identify that the recording is a TS stream :

  tstools/bin$ ./stream_type ~/recordings/20130129-202049
  
  Reading from /home/dustin/recordings/20130129-202049
  
  It appears to be Transport Stream

  ...but that there are no PAT/PMT frames :

  tstools/bin$ ./tsinfo ~/recordings/20130129-202049
  
  Reading from /home/dustin/recordings/20130129-202049
  
  Scanning 10000 TS packets
  
  
  
  Found 0 PAT packets and 0 PMT packets in 10000 TS packets

  I was able to produce a single ES (elementary stream) stream, by running ts2es :

  tstools/bin$ ./ts2es -pid 97 ~/recordings/20130129-202049 ~/recordings/20130129-202049.es
  
  Reading from /home/dustin/recordings/20130129-202049
  
  Writing to   /home/dustin/recordings/20130129-202049.es
  
  Extracting packets for PID 0061 (97)
  
  !!! 4 bytes ignored at end of file - not enough to make a TS packet
  
  Extracted 219258 of 248113 TS packets

  I am able to play the ES stream (even though the video is frozen on the first frame) :

  gst-launch-0.10 filesrc location=~/recordings/20130129-202049.es ! decodebin2 ! autovideosink
  
  gst-launch-0.10 filesrc location=~/recordings/20130129-202049.es ! decodebin2 ! xvimagesink
  
  gst-launch-0.10 playbin2 uri=file:///home/dustin/recordings/20130129-202049.es

  No matter what I do, though, I can't get the original TS file to open. However, it opens in Mplayer/FFMPEG, perfectly (but not VLC). This is the output of FFMPEG :

  ffmpeg -i 20130129-202049
  
  
  
  ffmpeg version 0.8.5-4:0.8.5-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the Libav developers
  
    built on Jan 24 2013 18:03:14 with gcc 4.6.3
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  
  [mpeg2video @ 0x9be7be0] mpeg_decode_postinit() failure
  
      Last message repeated 4 times
  
  [mpegts @ 0x9be3aa0] max_analyze_duration reached
  
  [mpegts @ 0x9be3aa0] PES packet size mismatch
  
  Input #0, mpegts, from '20130129-202049':
  
    Duration: 00:03:39.99, start: 9204.168844, bitrate: 1696 kb/s
  
      Stream #0.0[0x61]: Video: mpeg2video (Main), yuv420p, 528x480 [PAR 40:33 DAR 4:3], 15000 kb/s, 30.57 fps, 29.97 tbr, 90k tbn, 59.94 tbc
  
      Stream #0.1[0x64]: Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s
  
  At least one output file must be specified

  This tells us that the video stream has PID 0x61 (97).

  I have been trying for a few days, so the following are only examples of a couple of attempts. I'll provide the playbin2 example first, since I know that thousands of people will respond, insisting that I just use that. It doesn't work.

  gst-launch-0.10 playbin2 uri=file:///home/dustin/recordings/20130129-202049
  
  
  
  Setting pipeline to PAUSED ...
  
  Pipeline is PREROLLING ...
  
  ERROR: from element /GstPlayBin2:playbin20/GstURIDecodeBin:uridecodebin0/GstDecodeBin2:decodebin20/GstMpegTSDemux:mpegtsdemux0: Could not determine type of stream.
  
  Additional debug info:
  
  gstmpegtsdemux.c(2931): gst_mpegts_demux_sink_event (): /GstPlayBin2:playbin20/GstURIDecodeBin:uridecodebin0/GstDecodeBin2:decodebin20/GstMpegTSDemux:mpegtsdemux0:
  
  No valid streams found at EOS
  
  ERROR: pipeline doesn't want to preroll.
  
  Setting pipeline to NULL ...
  
  Freeing pipeline ...

  It fails [probably] because no PID has been specified with which to find the video (the "EOS" error, I think).

  Naturally, I tried the following to start by demuxing the TS format. I believe it's the "es-pids" property that receives the PID in the absence of PMT information (which tstools said there weren't any, above), but I tried "program-number", too, just in case. gst-inspect indicates that one is hex and the other is decimal :

  gst-launch-0.10 -v filesrc location=20130129-202049 ! mpegtsdemux es-pids=0x61 ! fakesink
  
  gst-launch-0.10 -v filesrc location=20130129-202049 ! mpegtsdemux program-number=97 ! fakesink

  Output :

  gst-launch-0.10 filesrc location=20130129-202049 ! mpegtsdemux es-pids=0x61 ! fakesink
  
  Setting pipeline to PAUSED ...
  
  Pipeline is PREROLLING ...
  
  ERROR: from element /GstPipeline:pipeline0/GstMpegTSDemux:mpegtsdemux0: Could not determine type of stream.
  
  Additional debug info:
  
  gstmpegtsdemux.c(2931): gst_mpegts_demux_sink_event (): /GstPipeline:pipeline0/GstMpegTSDemux:mpegtsdemux0:
  
  No valid streams found at EOS
  
  ERROR: pipeline doesn't want to preroll.
  
  Setting pipeline to NULL ...
  
  Freeing pipeline ...
  
  dustin@dustinmicro:~/recordings$ gst-launch-0.10 -v filesrc location=20130129-202049 ! mpegtsdemux es-pids=0x61 ! fakesink
  
  Setting pipeline to PAUSED ...
  
  Pipeline is PREROLLING ...
  
  ERROR: from element /GstPipeline:pipeline0/GstMpegTSDemux:mpegtsdemux0: Could not determine type of stream.
  
  Additional debug info:
  
  gstmpegtsdemux.c(2931): gst_mpegts_demux_sink_event (): /GstPipeline:pipeline0/GstMpegTSDemux:mpegtsdemux0:
  
  No valid streams found at EOS
  
  ERROR: pipeline doesn't want to preroll.
  
  Setting pipeline to NULL ...
  
  Freeing pipeline ...
  
  dustin@dustinmicro:~/recordings$ gst-launch-0.10 -v filesrc location=20130129-202049 ! mpegtsdemux es-pids=0x61 ! fakesink
  
  Setting pipeline to PAUSED ...
  
  Pipeline is PREROLLING ...
  
  ERROR: from element /GstPipeline:pipeline0/GstMpegTSDemux:mpegtsdemux0: Could not determine type of stream.
  
  Additional debug info:
  
  gstmpegtsdemux.c(2931): gst_mpegts_demux_sink_event (): /GstPipeline:pipeline0/GstMpegTSDemux:mpegtsdemux0:
  
  No valid streams found at EOS
  
  ERROR: pipeline doesn't want to preroll.
  
  Setting pipeline to NULL ...
  
  Freeing pipeline ...

  However, when I try mpegpsdemux (for program streams (PS), as opposed to transport streams (TS)), I get further :

  gst-launch-0.10 filesrc location=20130129-202049 ! mpegpsdemux ! fakesink
  
  
  
  Setting pipeline to PAUSED ...
  
  Pipeline is PREROLLING ...
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_event_new_new_segment_full: assertion `position != -1' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_mini_object_ref: assertion `mini_object != NULL' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_pad_push_event: assertion `event != NULL' failed
  
  Pipeline is PREROLLED ...
  
  Setting pipeline to PLAYING ...
  
  New clock: GstSystemClock
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_event_new_new_segment_full: assertion `position != -1' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_mini_object_ref: assertion `mini_object != NULL' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_pad_push_event: assertion `event != NULL' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_event_new_new_segment_full: assertion `position != -1' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_mini_object_ref: assertion `mini_object != NULL' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_pad_push_event: assertion `event != NULL' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_event_new_new_segment_full: assertion `position != -1' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_mini_object_ref: assertion `mini_object != NULL' failed
  
  
  
  (gst-launch-0.10:14805): GStreamer-CRITICAL **: gst_pad_push_event: assertion `event != NULL' failed
  
  
  
  
  
  ...
  
  
  
  
  
  Got EOS from element "pipeline0".
  
  Execution ended after 1654760008 ns.
  
  Setting pipeline to PAUSED ...
  
  Setting pipeline to READY ...
  
  Setting pipeline to NULL ...
  
  Freeing pipeline ...

  I'll still get the same problem whenever I use the mpegtsdemux, even if it follows mpegpsdemux, above.

  I don't understand this, since I haven't even picked a PID yet.

  What am I doing wrong ?

  Dustin

• How to make dynamic timestamp in ffpmeg, not static ?

  28 février 2013, par Sergii Rechmp

  I am using ffmpeg (windows pc) with my webcam to record what happens when i'm out of home.
  It works fine, but i can't make dynamic clock and date on screen.
  I have tried

  -vf "[in]drawtext=fontsize=12:fontfile=arial.ttf:text='%date%':x=10:y=25,  
  
  drawtext=fontsize=12:fontfile=arial.ttf:text="%TIME:~0,2%-%TIME:~3,2%-%TIME:~6,2%"

  It works, but it shows time only for start moment, than it wont change during video recording.
  it looks like :
  Is there any method to out time on screen ?
  Thanks.

• Decoding VP8 On A Sega Dreamcast

  20 février 2011, par Multimedia Mike — Sega Dreamcast, VP8

  I got Google’s libvpx VP8 codec library to compile and run on the Sega Dreamcast with its Hitachi/Renesas SH-4 200 MHz CPU. So give Google/On2 their due credit for writing portable software. I’m not sure how best to illustrate this so please accept this still photo depicting my testbench Dreamcast console driving video to my monitor :

  
  
  

  Why ? Because I wanted to try my hand at porting some existing software to this console and because I tend to be most comfortable working with assorted multimedia software components. This seemed like it would be a good exercise.

  You may have observed that the video is blue. Shortest, simplest answer : Pure laziness. Short, technical answer : Path of least resistance for getting through this exercise. Longer answer follows.

  Update : I did eventually realize that the Dreamcast can work with YUV textures. Read more in my followup post.

  Process and Pitfalls
  libvpx comes with a number of little utilities including decode_to_md5.c. The first order of business was porting over enough source files to make the VP8 decoder compile along with the MD5 testbench utility.

  Again, I used the KallistiOS (KOS) console RTOS (aside : I’m still working to get modern Linux kernels compiled for the Dreamcast). I started by configuring and compiling libvpx on a regular desktop Linux system. From there, I was able to modify a number of configuration options to make the build more amenable to the embedded RTOS.
  
  I had to create a few shim header files that mapped various functions related to threading and synchronization to their KOS equivalents. For example, KOS has a threading library cleverly named kthreads which is mostly compatible with the more common pthread library functions. KOS apparently also predates stdint.h, so I had to contrive a file with those basic types.

  So I got everything compiled and then uploaded the binary along with a small VP8 IVF test vector. Imagine my surprise when an MD5 sum came out of the serial console. Further, visualize my utter speechlessness when I noticed that the MD5 sum matched what my desktop platform produced. It worked !

  Almost. When I tried to decode all frames in a test vector, the program would invariably crash. The problem was that the file that manages motion compensation (reconinter.c) needs to define MUST_BE_ALIGNED which compiles byte-wise block copy functions. This is necessary for CPUs like the SH-4 which can’t load unaligned data. Apparently, even ARM CPUs these days can handle unaligned memory accesses which is why this isn’t a configure-time option.

  Showing The Work
  I completed the first testbench application which ran the MD5 test on all 17 official IVF test vectors. The SH-4/Dreamcast version aces the whole suite.

  However, this is a video game console, so I had better be able to show the decoded video. The Dreamcast is strictly RGB— forget about displaying YUV data directly. I could take the performance hit to convert YUV -> RGB. Or, I could just display the intensity information (Y plane) rendered on a random color scale (I chose blue) on an RGB565 texture (the DC’s graphics hardware can also do paletted textures but those need to be rearranged/twiddled/swizzled).

  Results
  So, can the Dreamcast decode VP8 video in realtime ? Sure ! Well, I really need to qualify. In the test depicted in the picture, it seems to be realtime (though I wasn’t enforcing proper frame timings, just decoding and displaying as quickly as possible). Obviously, I wasn’t bothering to properly convert YUV -> RGB. Plus, that Big Buck Bunny test vector clip is only 176x144. Obviously, no audio decoding either.

  So, realtime playback, with a little fine print.

  On the plus side, it’s trivial to get the Dreamcast video hardware to upscale that little blue image to fullscreen.

  I was able to tally the total milliseconds’ worth of wall clock time required to decode the 17 VP8 test vectors. As you can probably work out from this list, when I try to play a 320x240 video, things start to break down.

  1. Processed 29 176x144 frames in 987 milliseconds.
  2. Processed 49 176x144 frames in 1809 milliseconds.
  3. Processed 49 176x144 frames in 704 milliseconds.
  4. Processed 29 176x144 frames in 255 milliseconds.
  5. Processed 49 176x144 frames in 339 milliseconds.
  6. Processed 48 175x143 frames in 2446 milliseconds.
  7. Processed 29 176x144 frames in 432 milliseconds.
  8. Processed 2 1432x888 frames in 2060 milliseconds.
  9. Processed 49 176x144 frames in 1884 milliseconds.
  10. Processed 57 320x240 frames in 5792 milliseconds.
  11. Processed 29 176x144 frames in 989 milliseconds.
  12. Processed 29 176x144 frames in 740 milliseconds.
  13. Processed 29 176x144 frames in 839 milliseconds.
  14. Processed 49 175x143 frames in 2849 milliseconds.
  15. Processed 260 320x240 frames in 29719 milliseconds.
  16. Processed 29 176x144 frames in 962 milliseconds.
  17. Processed 29 176x144 frames in 933 milliseconds.