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#7 Ambience
16 octobre 2011, par
Mis à jour : Juin 2015
Langue : English
Type : Audio
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#6 Teaser Music
16 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Audio
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#5 End Title
16 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Audio
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#3 The Safest Place
16 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Audio
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#4 Emo Creates
15 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Audio
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#2 Typewriter Dance
15 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Audio
Autres articles (84)
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Sur d’autres sites (9017)
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How to encode a video from several images generated in a C++ program without writing the separate frame images to disk ?
29 janvier 2016, par ksb496I am writing a C++ code where a sequence of N different frames is generated after performing some operations implemented therein. After each frame is completed, I write it on the disk as IMG_%d.png, and finally I encode them to a video through ffmpeg using the x264 codec.
The summarized pseudocode of the main part of the program is the following one :
std::vector<int> B(width*height*3);
for (i=0; i/ void generateframe(std::vector<int> &, int)
generateframe(B, i); // Returns different images for different i values.
sprintf(s, "IMG_%d.png", i+1);
WriteToDisk(B, s); // void WriteToDisk(std::vector<int>, char[])
}
</int></int></int>The problem of this implementation is that the number of desired frames, N, is usually high (N 100000) as well as the resolution of the pictures (1920x1080), resulting into an overload of the disk, producing write cycles of dozens of GB after each execution.
In order to avoid this, I have been trying to find documentation about parsing directly each image stored in the vector B to an encoder such as x264 (without having to write the intermediate image files to the disk). Albeit some interesting topics were found, none of them solved specifically what I exactly want to, as many of them concern the execution of the encoder with existing images files on the disk, whilst others provide solutions for other programming languages such as Python (here you can find a fully satisfactory solution for that platform).
The pseudocode of what I would like to obtain is something similar to this :
std::vector<int> B(width*height*3);
video_file=open_video("Generated_Video.mp4", ...[encoder options]...);
for (i=0; icode></int>According to what I have read on related topics, the x264 C++ API might be able to do this, but, as stated above, I did not find a satisfactory answer for my specific question. I tried learning and using directly the ffmpeg source code, but both its low ease of use and compilation issues forced me to discard this possibility as a mere non-professional programmer I am (I take it as just as a hobby and unluckily I cannot waste that many time learning something so demanding).
Another possible solution that came to my mind is to find a way to call the ffmpeg binary file in the C++ code, and somehow manage to transfer the image data of each iteration (stored in B) to the encoder, letting the addition of each frame (that is, not "closing" the video file to write) until the last frame, so that more frames can be added until reaching the N-th one, where the video file will be "closed". In other words, call ffmpeg.exe through the C++ program to write the first frame to a video, but make the encoder "wait" for more frames. Then call again ffmpeg to add the second frame and make the encoder "wait" again for more frames, and so on until reaching the last frame, where the video will be finished. However, I do not know how to proceed or if it is actually possible.
Edit 1 :
As suggested in the replies, I have been documenting about named pipes and tried to use them in my code. First of all, it should be remarked that I am working with Cygwin, so my named pipes are created as they would be created under Linux. The modified pseudocode I used (including the corresponding system libraries) is the following one :
FILE *fd;
mkfifo("myfifo", 0666);
for (i=0; i/ void WriteToPipe(std::vector<int>, FILE *&fd)
fflush(fd);
fd=fclose("myfifo");
}
unlink("myfifo");
</int>WriteToPipe is a slight modification of the previous WriteToFile function, where I made sure that the write buffer to send the image data is small enough to fit the pipe buffering limitations.
Then I compile and write the following command in the Cygwin terminal :
./myprogram | ffmpeg -i pipe:myfifo -c:v libx264 -preset slow -crf 20 Video.mp4
However, it remains stuck at the loop when i=0 at the "fopen" line (that is, the first fopen call). If I had not called ffmpeg it would be natural as the server (my program) would be waiting for a client program to connect to the "other side" of the pipe, but it is not the case. It looks like they cannot be connected through the pipe somehow, but I have not been able to find further documentation in order to overcome this issue. Any suggestion ?
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Low latency video streaming on android
17 mai 2021, par Louis BlennerI'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.


I am able to read the video on another PC 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 example with Vlc.

I tried changing the preferences of Vlc to stream as fast as possible.

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 ?

-
mp4 Vj Animation video lagging hi res video
21 février 2020, par Ryan StoneI am trying to get a video to play inside a video tag at the top left hand corner of my page, it loads ok, the resolution is good and it seems to be looping but it is lagging very much, definatly not achieving 60fps it is in mp4 format and the resolution on the original mp4 is 1920x1080 it is a hi resolution vj free loop called GlassVein, you can see it if you search on youtube. On right clicking properties it comes up with the following inforamtion ;
Bitrate:127kbs
Data rate:11270kbps
Total bitrate:11398kbs
Audio sample rate is : 44khz
filetype is:VLC media file(.mp4)
(but i do not want or need the audio)& it also says 30fps, but I’m not sure i believe this as it runs smooth as butter on vlc media player no lagging, just smooth loop animation
I have searched on :https://trac.ffmpeg.org/wiki/Encode/AAC for encoding information but it is complete gobbldygook to me, I don’t understand a word its saying
My code is so far as follows ;
<video src="GlassVeinColorful.mp4" autoplay="1" preload="auto" class="Vid" width="640" height="360" loop="1" viewport="" faststart="faststart" mpeg4="mpeg4" 320x240="320x240" 1080="1080" 128k="128k">
</video>Does anyone know why this is lagging so much, or what I could do about it.
it is a quality animation and I don’t really want to loose an of its resolution or crispness.. the -s section was originally set to 1920x1080 as this is what the original file is but i have changed it to try and render it quicker...Any helpful sites, articles or answers would be great..
2020 Update
The Solution to this problem was to convert the Video to WebM, then use Javascript & a Html5 Canvas Element to render the Video to the page instead of using the video tag to embed the video.
Html
<section>
<video src="Imgs/Vid/PurpGlassVein.webm" type="video/webm" width="684" height="auto" muted="muted" loop="loop" autoplay="autoplay">
<source>
<source>
<source>
</source></source></source></video>
<canvas style="filter:opacity(0);"></canvas>
</section>Css
video{
display:none !important;
visibility:hidden;
}Javascript
const Canv = document.querySelector("canvas");
const Video = document.querySelector("video");
const Ctx = Canv.getContext("2d");
Video.addEventListener('play',()=>{
function step() {
Ctx.drawImage(Video, 0, 0, Canv.width, Canv.height)
requestAnimationFrame(step)
}
requestAnimationFrame(step);
})
Canv.animate({
filter: ['opacity(0) blur(5.28px)','opacity(1) blur(8.20px)']
},{
duration: 7288,
fill: 'forwards',
easing: 'ease-in',
iterations: 1,
delay: 728
})I’ve Also Used the Vanilla Javascript .animate() API to fade the element into the page when the page loads. But one Caveat is that both the Canvas and the off-screen Video Tag must match the original videos resolution otherwise it starts to lag again, however you can use Css to scale it down via transform:scale(0.5) ; which doesn’t seem to effect performance at all.
runs smooth as butter, and doesn’t loose any of the high resolution image.
Added a slight blur0.34px
onto it aswell to smooth it even more.Possibly could of still used ffmpeg to get a better[Smaller File Size] WebM Output file but thats something I’ll have to look into at a later date.