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    Ce plugin vise à gérer des sites de mise en ligne de documents de tous types.
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  • Prérequis à l’installation

    31 janvier 2010, par

    Préambule
    Cet article n’a pas pour but de détailler les installations de ces logiciels mais plutôt de donner des informations sur leur configuration spécifique.
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  • KLV data in RTP stream

    18 septembre 2013, par Ardoramor

    I have implemented RFC6597 to stream KLV is RTP SMPTE336M packets. Currently, my SDP looks like this :

    v=2
    
o=- 0 0 IN IP4 127.0.0.1
    
s=Unnamed
    
i=N/A
    
c=IN IP4 192.168.1.6
    
t=0 0
    
a=recvonly
    
m=video 8202 RTP/AVP 96
    
a=rtpmap:96 H264/90000
    
a=fmtp:96 packetization-mode=1;profile-level-id=428028;sprop-parameter-sets=Z0KAKJWgKA9E,aM48gA==;
    
a=control:trackID=0
    
m=application 8206 RTP/AVP 97
    
a=rtpmap:97 smpte336m/1000
    
a=control:trackID=1

    I try to remux the RTP stream with FFmpeg like so :

    ffmpeg.exe -i test.sdp -map 0:0 -map 0:1 -c:v copy -c:d copy test.m2ts

    I get the following output with FFmpeg :

    ffmpeg version 1.2 Copyright (c) 2000-2013 the FFmpeg developers
    
  built on Mar 28 2013 00:34:08 with gcc 4.8.0 (GCC)
    
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
    
  libavutil      52. 18.100 / 52. 18.100
    
  libavcodec     54. 92.100 / 54. 92.100
    
  libavformat    54. 63.104 / 54. 63.104
    
  libavdevice    54.  3.103 / 54.  3.103
    
  libavfilter     3. 42.103 /  3. 42.103
    
  libswscale      2.  2.100 /  2.  2.100
    
  libswresample   0. 17.102 /  0. 17.102
    
  libpostproc    52.  2.100 / 52.  2.100
    
[aac @ 0000000002137900] Sample rate index in program config element does not match the sample rate index configured by the container.
    
    Last message repeated 1 times
    
[aac @ 0000000002137900] decode_pce: Input buffer exhausted before END element found
    
[h264 @ 00000000002ce540] Missing reference picture, default is 0
    
[h264 @ 00000000002ce540] decode_slice_header error
    
[sdp @ 00000000002cfa80] Estimating duration from bitrate, this may be inaccurate
    
Input #0, sdp, from 'C:\Users\dragan\Documents\Workspace\Android\uvlens\tests\test.sdp':
    
  Metadata:
    
    title           : Unnamed
    
    comment         : N/A
    
  Duration: N/A, start: 0.000000, bitrate: N/A
    
    Stream #0:0: Audio: aac, 32000 Hz, 58 channels, fltp
    
    Stream #0:1: Video: h264 (Baseline), yuv420p, 640x480, 14.83 tbr, 90k tbn, 180k tbc
    
    Stream #0:2: Data: none
    
File 'C:\Users\dragan\Documents\Workspace\Android\uvlens\tests\test.m2ts' already exists. Overwrite ? [y/N] y
    
Output #0, mpegts, to 'C:\Users\dragan\Documents\Workspace\Android\uvlens\tests\test.m2ts':
    
  Metadata:
    
    title           : Unnamed
    
    comment         : N/A
    
    encoder         : Lavf54.63.104
    
    Stream #0:0: Video: h264, yuv420p, 640x480, q=2-31, 90k tbn, 90k tbc
    
    Stream #0:1: Data: none
    
Stream mapping:
    
  Stream #0:1 -> #0:0 (copy)
    
  Stream #0:2 -> #0:1 (copy)
    
Press [q] to stop, [?] for help
    
[mpegts @ 0000000002159940] Application provided invalid, non monotonically increasing dts to muxer in stream 1: 8583659665 >= 8583656110
    
av_interleaved_write_frame(): Invalid argument

    The problem is that KLV stream packets do not contain have a DTS field. According to the RFC6597 STMPE336M, RTP packet structure is the same as a standard structure :

    4.1.  RTP Header Usage
    

    
This payload format uses the RTP packet header fields as described in
    
the table below:
    

    
+-----------+-------------------------------------------------------+
    
| Field     | Usage                                                 |
    
+-----------+-------------------------------------------------------+
    
| Timestamp | The RTP Timestamp encodes the instant along a         |
    
|           | presentation timeline that the entire KLVunit encoded |
    
|           | in the packet payload is to be presented.  When one   |
    
|           | KLVunit is placed in multiple RTP packets, the RTP    |
    
|           | timestamp of all packets comprising that KLVunit MUST |
    
|           | be the same.  The timestamp clock frequency is        |
    
|           | defined as a parameter to the payload format          |
    
|           | (Section 6).                                          |
    
|           |                                                       |
    
| M-bit     | The RTP header marker bit (M) is used to demarcate    |
    
|           | KLVunits.  Senders MUST set the marker bit to '1' for |
    
|           | any RTP packet that contains the final byte of a      |
    
|           | KLVunit.  For all other packets, senders MUST set the |
    
|           | RTP header marker bit to '0'.  This allows receivers  |
    
|           | to pass a KLVunit for parsing/decoding immediately    |
    
|           | upon receipt of the last RTP packet comprising the    |
    
|           | KLVunit.  Without this, a receiver would need to wait |
    
|           | for the next RTP packet with a different timestamp to |
    
|           | arrive, thus signaling the end of one KLVunit and the |
    
|           | start of another.                                     |
    
+-----------+-------------------------------------------------------+
    

    
The remaining RTP header fields are used as specified in [RFC3550].

    Header from RFC3550 :

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    
|V=2|P|X|  CC   |M|     PT      |       sequence number         |
    
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    
|                           timestamp                           |
    
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    
|           synchronization source (SSRC) identifier            |
    
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
    
|            contributing source (CSRC) identifiers             |
    
|                             ....                              |
    
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    RFC's note about placement of KLV data into RTP packet :

    KLVunits small enough to fit into a single RTP
    packet (RTP packet size is up to the implementation but should
    consider underlying transport/network factors such as MTU
    limitations) are placed directly into the payload of the RTP packet,
    with the first byte of the KLVunit (which is the first byte of a KLV
    Universal Label Key) being the first byte of the RTP packet payload.

    My question is where does FFmpeg keep looking for the DTS ?

    Does it interpret the Timestamp field of the RTP packet header as DTS ? If so, I've verified that the timestamps increase (although at different rates) but are not equal to what FFmpeg prints out :

    8583659665 >= 8583656110

  • Revision 5215b83aea : Simplifying and inlining k_cvtlo_epi16 and k_cvthi_epi16 Simplify the k_cvtlo_e

    3 octobre 2013, par A.Mahfoodh

    Changed Paths :
     Modify /vp9/encoder/x86/vp9_dct32x32_sse2.c



    Simplifying and inlining k_cvtlo_epi16 and k_cvthi_epi16

    Simplify the k_cvtlo_epi16 and k_cvthi_epi16 to only two
    instructions. Then inlined them.

    quoting from intel MMX_App_Compute_16bit_Vector.pdf‎
    "The PMADDWD instruction multiplies four
    pairs of 16-bit numbers and produces partial sums of the results
    and can do so once per clock (with a three-clock latency)."
    so I am assuming that there will be three clock overhead after the
    last _mm_madd_pi16 command.
    Even with the overhead the number of clocks in general should be
    smaller. I am not sure though becasue I could not find information
    about number of clocks required for instructions in k_cvtlo_epi16
    and k_cvthi_epi16. I will run a test and compare the execution time.

    Change-Id : Ieda4aa338f69ad3dd196ac6e7892da3cf1b47ea7

  • ffmpeg-How to burn subtitles into the video

    28 décembre 2013, par user3141070

    Sir i want to burn subtitles into video.
    i use this command

    ffmpeg -i video.avi -vf subtitles=subtitle.srt out.avi

    but nothing is burn on video.
    My video is 30 sec.
    and my srt file is like this

    1
    
00:00:04,700 --> 00:00:06,736
    
where are you going so early?
    

    
2
    
00:00:06,900 --> 00:00:09,494
    
Don't record any more messages
    
on my alarm clock.
    

    
3
    
00:00:09 --> 00:00:11
    
why not?
    

    
4
    
00:00:11 --> 00:00:13
    
I'll start to think we're married
    
or something.
    

    
5
    
00:00:14 --> 00:00:15
    
Don't ever say that word.
    

    
6
    
00:00:15 --> 00:00:20
    
I'll never bring you chicken soup
    
and fuck your brains out again.
    

    
7
    
00:00:20--> 00:00:25
    
- How's your cold?
    
- Still there. How about yours?
    

    
8
    
00:00:25 --> 00:00:29
    
- You definitely took my mind off it.
    
- Really?

    so what's the problem ?

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