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Questions tagged [codec]

Codec is an implementation of compression and decompression of digital data streams and signals in different scales. Digital data like audio, video and electronic documents are been compressed and decompressed using codecs.

A codec can consist of two components: an encoder and a decoder. The encoder performs the compression (encoding) function and the decoder performs the decompression (decoding) function. Some codecs include both of these components and some codecs only include one of them.

There is mainly two kind of data compression technique.

  1. Lossless
  2. Lossy

Lossless Data Compression
Lossless data compression allows the exact original data to be reconstructed from the compressed data.

Lossy Data Compression
Lossy compression is a data encoding method that compresses data by discarding (losing) some of it. The procedure aims to minimize the amount of data that need to be held, handled.

List of Different Codecs
Wikipedia Codec List According to Catagory

FAQs
FAQ about Codecs by Microsoft
Codec Guide FAQ

Other Useful Links
Microsoft codec programming guide
ffmpeg codec programming
Codecguide

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How to extract PCM samples from MediaCodec decoder's output

I'm trying to obtain the PCM samples for further processing from a decoded mp4 buffer. I'm first extracting the audio track from a video file recorded with the phone's camera app, and I've made sure the audio track is being selected when I get the…
jimijazz
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Is re-encoding JPEG images an idempotent operation?

I am aware that JPEG compression is lossy. I have 2 questions: Given an operation T: 1. Take a JPEG-80 image 2. Decode it to a byte buffer 3. Encode given byte buffer as JPEG-80 Is T an idempotent operation in terms of visual quality? Or will the…
Sau
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H264 encoder in android?

I've been having some problems while trying to fix a simple video recording app*. I think I followed the sequence of steps correctly. The following is a simplification of the part of the code that is giving me problems. This code is executed only as…
Bilthon
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Print to UTF-8 encoded file, with platform-dependent newlines?

In Python, what is the best way to write to a UTF-8 encoded file with platform-dependent newlines? the solution would ideally work quite transparently in a program that does a lot of printing in Python 2. (Information about Python 3 is welcome…
Eric O. Lebigot
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Why does mp4 video plays fine on iPad, not on iPhone?

I'm quite stumped on this issue. I have a large library of H.264 mp4 video files that I need to have play on iOS. Originally, I was targeting only iPad, but requirements have changed and now I need to include iPhone. But I've noticed that my iPod…
Andrew
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H.264 Streaming Requirements

I am looking for more information about the minimum requirements needed for a visitor to successfully stream a 1 Mbps 640x360 H.264-encoded video. I know that the user needs the latest Flash 9 version. I am looking for the minimum requirements for…
user24632
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Adding new CODEC to ffmpeg

Is it possible to add new codec's to ffmepg? i searched a bit and was not able to find any concrete answer about this. If possible, Can i know the steps?
Gopi
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Installing codecs for mov to mp4 conversion ffmpeg

I have been trying to convert a .mov file to a .mp4 file for a while now i think this is the correct code to do it. ffmpeg -i P1010989.MOV -vcodec copy -acodec copy out.mp4 But here is my output FFmpeg version 0.6.5, Copyright (c) 2000-2010 the…
user1503606
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FFmpeg fourcc Avi codec support list?

A couple of similar questions are on stackoverflow, but I haven't been able to figure this exact problem out. I want to get a list of the fourccs for the avi codecs that FFMpeg can decode. I know how to get all the formats ffmpeg -formats and codecs…
Sugrue
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Generate video from numpy arrays with openCV

I am trying to use the openCV VideoWriter class to generate a video from numpy arrays. I am using the following code: import numpy as np import cv2 size = 720*16//9, 720 duration = 2 fps = 25 out = cv2.VideoWriter('output.avi',…
daVinci
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Playback 24bit audio not possible

I'm trying to play a 24bit audio file with my AutoHotkey app. It just uses SoundPlay. Windows 7 has no problem, however Windows XP users cannot play the 24bit files. The documentation says: All Windows OSes should be able to play .wav files.…
svandragt
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Why is VideoDataOutput's availableVideoCodecTypes empty?

AVCaptureVideoDataOutput has a field availableVideoCodecTypes that's supposed to tell you what codecs you can use to record a video, but it's always empty. Why is this? I checked its value immediately after creating the VideoDataOutput, and after…
Kartick Vaddadi
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How to speed up OpenH264's decoder

Story I'm working on a smooth 60 FPS 1080p (Full HD) video transfer application that encodes in x264, sends the encoded data via LAN to a receiving device, which then decodes it using the OpenH264's decoder. I managed to get it working, and it works…
Roland
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How do I write raw binary data in Python?

I've got a Python program that stores and writes data to a file. The data is raw binary data, stored internally as str. I'm writing it out through a utf-8 codec. However, I get UnicodeDecodeError: 'charmap' codec can't decode byte 0x8d in…
Chris B.
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How to inspect H264/AVC ISO/IEC 14496-15 AVCDecoderConfigurationRecord?

Some historic background: I'm currently working with Wowza and attempting to decode the AMFPackets that come from the IMediaStream. The video packets will have a 5-byte header and the first packet is the codec configuration. So far in my inspecting…
Rob Olmos
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