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Questions tagged [video-codecs]

Questions related to video compression and decompression methods. This includes popular video codec standards like H.264, MPEG4.

A video codec is a device or software that enables video compression or decompression for digital video. The compression usually employs lossy data compression.

More details at http://en.wikipedia.org/wiki/Video_codec

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Implement Smooth Video Scrubbing with QMediaPlayer?

I have an application that is a fairly traditional "media player." It is implemented for Windows in C++17 with Qt5 providing the GUI. One of the "key" features is a progress slider you can grab to scrub to any position in the video. (This is…
DiB
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3GP video with "jpeg" video codec

I have cheap feature phone which can record videos in 3gp file format. When I upload such video to computer and inspect it with mediainfo it gives mysteriuos output: Format : MPEG-4 Format profile …
Never Man
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OpenCV VideoWriter issue crashing on iOS - info.backendFactory.empty() in function 'open'

I'm using cv::VideoWriter from OpenCV 3.5.2 class to read a file and write it into another file, with a lower FPS rate. However, when calling cv::VideoWriter videoWriter = cv::VideoWriter(); videoWriter.open( outputFilePath.UTF8String, …
Tiago Ornelas
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Python video decoding _without_ open-cv

I'm creating a lightweight application that should act as a shallow user interface to configure a camera and preview its video stream. The stream comes YUV- or Motion-JPEG encoded (and maybe some others), and I would want to display it into a…
xtofl
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ffmpeg - maintain video quality as I apply multi-pass workflow, each includes decoding and encoding again, in video editing

I'm using FFMPEG libraries do do some video manipulation, and due to complexity of filters and image overlaying, I have to run the process in multiple passes. This means, my process is as such: Open original video, decode it, run -complex_filter,…
QRrabbit
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ffmpeg error on DVCPRO HD encoding is not supported

Please help, I'm trying to encode a video stream, and output the video using the same format as my input: ffmpeg -i input.mov -c:v dvvideo -pix_fmt yuv422p -b:v 115084915 -maxrate 115084915 -minrate 115084915 -r 29.97 -top 1 -color_primaries bt709…
QRrabbit
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why B frame only 50:1 compression ratio, but h264 can have 250:1 compression ratio?

I'm learning some knowledge about video coding and now I know I frame has about 7:1 compression ration, P frame has about 20:1 compression ratio, B frame has 50:1 compression ratio, but why h264 has 250:1 compression ratio, it seems it uses some…
user6853157
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how to optimize x264 for online live education scene？

I am working on a x264 optimization project for online live education. Often, the teachers are sitting before the camera, and doesn't have big motion, and the background are the same (exception light changes). And is there some papers that I can…
Longshan DU
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I've been trying to create a video from numpy arrays using OpenCv. It gives a "corrupted" file most of the time

For some reason some resolutions work and others don't. Many codec-container combinations work but some don't. I know not all containers work with all codecs but it seems weird. The code below is a version with the same behavior. import cv2 import…
iftach freund
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How to get the VP9 decoder from a C++ program on Hololens 2?

I am implementing a VP9 hardware decoder that will run on PC and Hololens 2. When I try to load the "MSVP9DEC.dll", it works well on PC but the DLL is not found on Hololens. I have installed the VP9 Video Extensions on the device. Here the snipped…
Cloyz
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FFMPEG Video loop from images files

I am trying to make a video from a bundle of image files and then apply a an overlay on top of it.Another requirement is to make the video loop 3x. It is simply not working. The first three paths are pointing toward the same image bundle. (A folder…
Nesan Mano
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How to depacketize the fragmented frames in RTP data (over UDP) for H265/HEVC?

I am trying to depacketize a raw RTP H265 stream and reconstruct it so that it can be read by a decoder. I have been able to extract individual and fragmented units from the RTP buffers by identifying the NALs and FU details. However, I couldn't…
Old Markus
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OpenCV video writer unable to find codec or "avc1"

I am trying to write a video with cv2 in Python3 and I get the following message: "Could not find encoder for codec id 27: Encoder not found". Here's my code: video_writer = cv2.VideoWriter() video_writer.open(filename,…
Blackgold97
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QMediaPlayer displays audio only for certain videos

I'm using QMediaPlayer according to the example in the docs. Here's my code: from PySide2 import QtWidgets from PySide2 import QtCore from PySide2.QtMultimedia import QMediaPlayer from PySide2.QtMultimediaWidgets import QVideoWidget class…
Blimmo
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m3u8 stream playing can be of different codec dependent

New in streaming m3u8 files. Was working on webos tv based application. Where can play m3u8 files, but came across some m3u8 files are playing but not all. Here is one example , This is working code in html chrome browser: …
Maninder Birhe
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