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• Decoder return of av_find_best_stream vs. avcodec_find_decoder

  7 octobre 2016, par Jason C

  The docs for libav’s av_find_best_stream function (libav 11.7, Windows, i686, GPL) specify a parameter that can be used to receive a pointer to an appropriate AVCodec :

  decoder_ret - if non-NULL, returns the decoder for the selected stream

  There is also the avcodec_find_decoder function which can find an AVCodec given an ID.

  However, the official demuxing + decoding example uses av_find_best_stream to find a stream, but chooses to use avcodec_find_decoder to find the codec in lieu of av_find_best_stream’s codec return parameter :

  ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
  
  ...
  
  stream_index = ret;
  
  st = fmt_ctx->streams[stream_index];
  
  ...
  
  /* find decoder for the stream */
  
  dec = avcodec_find_decoder(st->codecpar->codec_id);

  As opposed to something like :

  ret = av_find_best_stream(fmt_ctx, type, -1, -1, &dec, 0);

  My question is pretty straightforward : Is there a difference between using av_find_best_stream’s return parameter vs. using avcodec_find_decoder to find the AVCodec ?

  The reason I ask is because the example chose to use avcodec_find_decoder rather than the seemingly more convenient return parameter, and I can’t tell if the example did that for a specific reason or not. The documentation itself is a little spotty and disjoint, so it’s hard to tell if things like this are done for a specific important reason or not. I can’t tell if the example is implying that it "should" be done that way, or if the example author did it for some more arbitrary personal reason.

• avutil/dovi_meta : add dolby vision extension blocks

  23 mars 2024, par Niklas Haas

  avutil/dovi_meta : add dolby vision extension blocks
  As well as accessors plus a function for allocating this struct with
  
  extension blocks,
  Definitions generously taken from quietvoid/dovi_tool, which is
  
  assembled as a collection of various patent fragments, as well as output
  
  by the official Dolby Vision bitstream verifier tool.
  

  • [DH] doc/APIchanges
  • [DH] libavutil/dovi_meta.c
  • [DH] libavutil/dovi_meta.h
  • [DH] libavutil/version.h

• Cannot stream video from VLC docker

  4 avril 2023, par Snake Eyes

  I have Dockerfile :

  


  FROM fedora:34

ARG VLC_UID="1000"
ARG VLC_GID="1000"

ENV HOME="/data"


RUN groupadd -g "${VLC_GID}" vlc && \
    useradd -m -d /data -s /bin/sh -u "${VLC_UID}" -g "${VLC_GID}" vlc && \
    dnf upgrade -y && \
    rpm -ivh "https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-34.noarch.rpm" && \
    dnf upgrade -y && \
    dnf install -y vlc && \
    dnf install -y libaacs libbdplus && \
    dnf install -y libbluray-bdj && \
    dnf clean all

USER "vlc"

WORKDIR "/data"

VOLUME ["/data"]

ENTRYPOINT ["/usr/bin/cvlc"]


  


  And then run :

  


  docker run -d -v "d:\path":/data -p 8787:8787 myrepo/myvlc:v1 file:///data/Sample.mkv --sout '#transcode {vcodec=h264,acodec=mp3,samplerate=44100}:std{access=http,mux=ffmpeg{mux=flv},dst=0.0.0.0:8787/stream.flv}'


  


  I get error :

  


  2023-04-04 12:19:11 [000055933c090060] vlcpulse audio output error: PulseAudio server connection failure: Connection refused
2023-04-04 12:19:11 [000055933c09d680] dbus interface error: Failed to connect to the D-Bus session daemon: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
2023-04-04 12:19:11 [000055933c09d680] main interface error: no suitable interface module
2023-04-04 12:19:11 [000055933bf26ad0] main libvlc error: interface "dbus,none" initialization failed
2023-04-04 12:19:11 [000055933c08d7a0] main interface error: no suitable interface module
2023-04-04 12:19:11 [000055933bf26ad0] main libvlc error: interface "globalhotkeys,none" initialization failed
2023-04-04 12:19:11 [000055933c08d7a0] dummy interface: using the dummy interface module...
2023-04-04 12:19:11 [00007f3b84001250] stream_out_standard stream out error: no mux specified or found by extension
2023-04-04 12:19:11 [00007f3b84000f30] main stream output error: stream chain failed for `standard{mux="",access="",dst="'#transcode"}'
2023-04-04 12:19:11 [00007f3b90000c80] main input error: cannot start stream output instance, aborting
2023-04-04 12:19:11 [00007f3b7c001990] stream_out_standard stream out error: no mux specified or found by extension
2023-04-04 12:19:11 [00007f3b7c001690] main stream output error: stream chain failed for `standard{mux="",access="",dst="'#transcode"}'
2023-04-04 12:19:11 [00007f3b90000c80] main input error: cannot start stream output instance, aborting


  


  I mention that I'm using cvlc and I can't stream that mkv file.

  


  I tried as well --sout '#transcode{scodec=none}:http{mux=ffmpeg{mux=flv},dst=:8787/}' but same errors.

  


  How can I solve it ?