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• Low latency video player on android

  20 mai 2021, par Louis Blenner

  I'd like to be able to stream the video from my webcam to an Android app with a latency below 500ms, on my local network.

  


  To capture and send the video over the network, I use ffmpeg.

  


  ffmpeg -f v4l2 -i /dev/video0 -preset ultrafast -tune zerolatency -vcodec libx264 -an -vf format=yuv420p -f mpegts  udp://192.168.1.155:5000


  


  This command takes the webcam as an input, convert it and send it to a device using the mpegts protocol.
  
This is not a requirement, if another technique could work, I could change the way I send the video.

  


  I am able to read the video on another PC from the local network with a latency below 500 ms, using commands like

  


  gst-launch-1.0 -v udpsrc port=5000 ! video/mpegts ! tsdemux ! h264parse ! avdec_h264 ! fpsdisplaysink sync=false


  


  or

  


  mpv udp://0.0.0.0:5000 --no-cache --untimed --no-demuxer-thread --video-sync=audio --vd-lavc-threads=1 


  


  So it is possible to have this range of latency.
  
I'd like to have the same thing on Android.

  


  Here are my tries to do that.

  


  Exoplayer

  


  After looking at the different players available on Android studio, it seems like Exoplayer is the go-to choice.
  
I tried different options indicated in the live-streaming documentation, but I always end up with a stream taking seconds to start and with a latency of seconds.
  
I tried to add a Button to seek to the default position of the windows, but it results in a loading of several seconds.

  


  DefaultExtractorsFactory extractorsFactory =
                new DefaultExtractorsFactory()
                        .setTsExtractorFlags(DefaultTsPayloadReaderFactory.FLAG_IGNORE_AAC_STREAM);

        player = new SimpleExoPlayer.Builder(this)
                .setMediaSourceFactory(
                        new DefaultMediaSourceFactory(this, extractorsFactory))
                .setLoadControl(new DefaultLoadControl.Builder()
                        .setBufferDurationsMs(DefaultLoadControl.DEFAULT_MIN_BUFFER_MS, DefaultLoadControl.DEFAULT_MAX_BUFFER_MS, 200, 200)
                        .build())
                .build();
        MyPlayerView playerView = findViewById(R.id.player_view);
        // Bind the player to the view.
        playerView.setPlayer(player);
        // Build the media item.
        MediaItem mediaItem = new MediaItem.Builder()
                .setUri(Uri.parse("udp://0.0.0.0:5000"))
                .setLiveMaxOffsetMs(500)
                .setLiveTargetOffsetMs(0)
                .setLiveMinOffsetMs(0)
                .build();
        // Set the media item to be played.
        player.setMediaItem(mediaItem);
        // Prepare the player.
        player.setPlayWhenReady(true);
        player.prepare();
        //player.seekToDefaultPosition();


  


  This issue is about the same issue and the conclusion was that Exoplayer was not fit for this use case.

  


  


  I'll be honest, ultra low-latency like this isn't ExoPlayer's main use-case

  


  


  Vlc

  


  Another try was to use the Vlc library.
  
But I was unable to have the same low latency stream as with the two previous players with Vlc.
  
I tried changing the preferences of Vlc to stream as fast as possible as described here

  


  Input/Codecs -> x264 preset: ultrafast - zerolatency
Input/Codecs -> Access Module: UDP input
Input/Codecs -> Clock Jitter: 500
Audio: disable audio


  


  I also tried reducing the different buffers.
  
However, I still have a latency of more than 1 seconds with that.

  


  Gstreamer

  


  Another try was to create a react-native project to use the different players available here.
  
One player that seemed promising was react-native-gstreamer because it uses gstreamer which is able to stream with low latency (gst-launch command).
  
But the library is now outdated.

  


  Question

  


  There were other tries, but none were successful.
  
Is there a problem with one of my approaches ?
  
And if not, Is there a player on Android (that I missed) which is able to achieve low latency stream like gstream or mpv on linux ?

  


• Pims.open Throws "UnkownFormat Error" with "Invalid Argument" On One Machine But Not on Another

  12 août 2021, par KaceBellamy

  I'm trying to do some video processing for a physics experiment, and I want to do it on my much more powerful Windows desktop computer as opposed to my Mac laptop.

  


  The following code works like a dream when run as a Jupyter notebook on my Mac :

  


  import matplotlib as mpl
from mpl_toolkits import mplot3d
import pims
import trackpy as tp 

@pims.pipeline
def gray(image):
    return image[:, :, 1]  # Take just the green channel

frames = gray(pims.open('output.mp4'))


  


  but on my Windows machine I get this error :

  


  ---------------------------------------------------------------------------&#xA;UnknownFormatError                        Traceback (most recent call last)&#xA;~\AppData\Local\Temp/ipykernel_12152/704954007.py in <module>&#xA;      1 #Actually converts the video. Might be VERY processor intensive... or not?&#xA;----> 2 frames = gray(pims.open(&#x27;output.mp4&#x27;)) #Make the File Name whatever file you like!&#xA;&#xA;~\miniconda3\lib\site-packages\pims\api.py in open(sequence, **kwargs)&#xA;    207             warn(message)&#xA;    208             exceptions &#x2B;= message &#x2B; &#x27;\n&#x27;&#xA;--> 209     raise UnknownFormatError("All handlers returned exceptions:\n" &#x2B; exceptions)&#xA;    210 &#xA;    211 &#xA;&#xA;UnknownFormatError: All handlers returned exceptions:&#xA;<class> errored: [Errno 22] Invalid argument: &#x27;output.mp4&#x27;&#xA;<class> errored: [Errno 22] Invalid argument: &#x27;output.mp4&#x27;&#xA;<class> errored: Could not load meta information&#xA;=== stderr ===&#xA;&#xA;ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers&#xA;  built with gcc 9.2.1 (GCC) 20200122&#xA;  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt&#xA;  libavutil      56. 31.100 / 56. 31.100&#xA;  libavcodec     58. 54.100 / 58. 54.100&#xA;  libavformat    58. 29.100 / 58. 29.100&#xA;  libavdevice    58.  8.100 / 58.  8.100&#xA;  libavfilter     7. 57.100 /  7. 57.100&#xA;  libswscale      5.  5.100 /  5.  5.100&#xA;  libswresample   3.  5.100 /  3.  5.100&#xA;  libpostproc    55.  5.100 / 55.  5.100&#xA;C:\Users\Callum\OneDrive - The University of Chicago\output.mp4: Invalid argument&#xA;<class> errored: MoviePy error: failed to read the duration of file output.mp4.&#xA;Here are the file infos returned by ffmpeg:&#xA;&#xA;ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers&#xA;  built with gcc 9.2.1 (GCC) 20200122&#xA;  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt&#xA;  libavutil      56. 31.100 / 56. 31.100&#xA;  libavcodec     58. 54.100 / 58. 54.100&#xA;  libavformat    58. 29.100 / 58. 29.100&#xA;  libavdevice    58.  8.100 / 58.  8.100&#xA;  libavfilter     7. 57.100 /  7. 57.100&#xA;  libswscale      5.  5.100 /  5.  5.100&#xA;  libswresample   3.  5.100 /  3.  5.100&#xA;  libpostproc    55.  5.100 / 55.  5.100&#xA;output.mp4: Invalid argument&#xA;</class></class></class></class></module>

  


  output.mp4 is just a run of the mill video file taken on a CCD camera ; I've tried converting it to a .MOV, I've tried other video files taken on different cameras, and I've tried running the file through FFmpeg to impose a 30 fps framerate ; everything I've tried works fine on my Mac and throws the above error on my Windows machine.

  


  For reference, I installed necessary packages for this code on both machines this morning, so it should all be up to date and the same on both.

  


  Any ideas as to what's up ? Thanks !

  


• FFMPEG and FFPlay can access rtsp stream from one ip, but from other ip, it can't

  28 mai 2022, par Crear

  The situation is kind of complex. I was archiving several CCTV camera feeds (rtsp, h264, no audio) through OpenCV, which worked but the CPU utilization was too high and started to lose some frames time by time.

  


  To reduce the CPU utilization, I started to use FFMPEG to skip the decoding and encoding processes, which worked perfectly on my home machine. However, when I connected to my university VPN and tried to deploy it on our lab server, FFmpeg couldn't read any frame, ffplay couldn't get anything either. However, OpenCV, VLC Player and IINA Player could still read and display the feed.

  


  In Summary,

  


  1 FFMPEG/ffplay

  


  1.1 can only read the feed from my home network(Wi-Fi, optimum)

  


  1.2 from other two networks, the error message says : "Could not find codec parameters for stream 0 (Video : h264, none) : unspecified size
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options"

  


  2 IINA/VLC Player, OpenCV
These tools can get the video all the time.

  


  I'm wondering whether it's related to some specific port access, that the ffmpeg required but the others don't. I'd appreciate it if anyone can provide any suggestions.

  


  As references, the tested ffplay command is simple :

  


  ffplay 'the rtsp address'


  


  Thanks

  


  ---

  


  Update

  


  More tests have been performed.

  


  By specifying rtsp_transport as TCP, ffplay can play the video, but FFmpeg can't access the video. (In the beginning, when both FFmpeg and ffplay worked through my home network, it was UDP)
The FFmpeg command is as follows :

  


  ffmpeg -i rtsp://the_ip_address/axis-media/media.amp -hide_banner -c:v copy -s 1920x1080 -segment_time 00:30:00 -f segment -strftime 1 -reset_timestamps 1 -rtsp_transport tcp "%Y-%m-%d-%H-%M-%S_Test.mp4"


  


  Please help...