Questions tagged [pcm]

PCM (Pulse-code modulation) is a method used to represent digital samples of the analog signals.

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Decoding aac to PCM in ffmpeg introduces noise in the raw PCM audio

I have a .mp4 file generated with ffmpeg as follows. ffmpeg -y -i video_extended.mp4 -itsoffset 00:00:04.00 -i output5-1.wav -map 0:0 -map 1:0 -c:v copy -c:a aac -ac 6 -ar 48000 -b:a 128k -async 1 ...
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How does G729 Codec compress down to 8kbps?

As per https://en.wikipedia.org/wiki/G.729: It has a sample frequency of 8kHz, so every second it takes 8000 Samples: Sampling frequency 8 kHz/16-bit (80 samples for 10 ms frames) It has a fixed ...
Flying Thunder's user avatar
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Convert raw AAC data to PCM data via ffmpeg

I have a system which is transmitting raw AAC data via TCP (no ADTS frame/header). Each "packet" is prefixed with enough information for me to determine the length of the raw data. I also ...
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How to convert flac inside mkv ffmpeg?

Guys! I was wanting to know if anyone can tell me how to losslessly convert FLAC audio to LPCM without any quality loss at all? This is info from of the mkv. Stream #0:0: Video, Stream #0:1: Audio: ...
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ALSA snd_pcm_hw_params_any crashed when auto-run from startup script

I downloaded the ALSA sample source codes (https://gist.github.com/ghedo/963382) and test running under putty window, it works. However when put into the startup script (eg. rc.local) with or without &...
runningdog's user avatar
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ffmpeg says "pcm_f32be codec not supported in WAVE format" yet a file is created

I'm trying to create a sine wave in .wav using ffmpeg exactly like this S.E. question: How to generate a sine wave with ffmpeg? For some sample formats it's working good but for big endian encoding, ...
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Extracting audio, don't understand PCM options

I've got the audio bitdepth, frequency and channels down. Pretty simple to understand, but cannot find enough information on the different PCM formats. I do understand the numbers correlate to the ...
Sea Maiden's user avatar
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ffmpeg - How to prevent innacurate duration when converting from pcm to wav?

I have the following command: ffmpeg -f f32le -ar 44100 -channels 2 -i input.pcm -y -acodec pcm_s16le -f wav output.wav input.pcm is the pcm data that comes from a 2 seconds wav file. However, when ...
Maxime Dupré's user avatar
2 votes
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How to encode into WAV ADPCM?

How to encode WAV PCM into WAV with ADPCM encoding? I tried FFmpeg. I can see from the old FFmpeg codec list, that it previously supported encoding into adpcm_adx, adpcm_ima_qt, adpcm_ima_wav, ...
Andriy Makukha's user avatar
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How to convert raw PCM data to a valid WAV file with ffmpeg?

I run this command: ffmpeg -f f32le -i pipe:0 -f wav pipe:1 ffmpeg version 4.1-tessus https://evermeet.cx/ffmpeg/ Copyright (c) 2000-2018 the FFmpeg developers built with Apple LLVM version 10.0.0 (...
Maxime Dupré's user avatar
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Using a ALSA PCM as an input device for Chromium?

I have a Matrix Creator which I want to use as an input for a speech to text platform, running through Chromium (using webkitSpeechRecognition). My problem is that I do not have it available as a ...
Timon Lukas's user avatar
3 votes
1 answer
10k views

FFmpeg raw audio and H264 in RTSP

Trying to grab correctly video and audio data from an IP camera Hikvision. Everything works like a charm when doing so for H264 + MP2 for example. When trying to grab RAW audio in PCM s16le - smile ...
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How accurate and reliable is loudness analysis (ebur128) in ffmpeg for PCM?

I need to test a lot of files on possible audio normalization issues, files can be of various containers and audio encoding formats but mostly PCM audio. I tried Rhozet QC solution but found it ...
user3223738's user avatar
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Is WAV (PCM) format bit rate is really CBR?

You know, all modern audio codecs bit rate modes are VBR, even if you restrict the settings to for example: MP3 128 CBR, the encoded result is between 120 to 135 ( a bit different with different ...
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How to extract Blu-ray audio without any conversion?

As avconv (forked from ffmpeg) said, the format of Blu-ray audio stream is called pcm_bluray, but why most of the tutorials say using -acodec pcm_s**le flag (** depends on its sample rate)? Are they ...
Kevin Dong's user avatar
8 votes
2 answers
4k views

Why Is Conversion From An MP3 To WAV (PCM) Lossless?

I understand that when converting between audio formats where no stream encoding is involved like when converting between WAV (PCM), AIFF, FLAC, ALAC, WMA Lossless, and etc, the process is usually ...
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Many microphones in windows

I need to record from as many as 40 microphones simultaneously on a single Windows 7 PC. These microphones will be present as USB audio adapters connected to powered USB hubs (so limited power isn't ...
William Morrison's user avatar
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ffmpeg option, subchunk1size = 16

I have a wav file. How can I use ffmpeg with specific options to convert it to a wave file with subchunk1size = 16.
Kelvin Tan's user avatar
2 votes
1 answer
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How to stream desktop through audio jack (3.5) using dsp

Is it possible to stream my desktop over audio system? I mean some kind of cat /dev/fb0 > /dev/dsp? Or to pulse-code my desktop using built-in soundcard and to stream it over optical spdif audio-...
illreality's user avatar
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2 answers
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How to convert PCM to MP3?

I have some .pcm files and I want to convert them to high quality .mp3 format. How can I do that? I've tried searching online but haven't found any programs that can do this. Ay suggestions? ...
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HDMI video stream

I am trying to determine the format of the audio portion of a video being sent from a digital device (DVD player, DVR, etc.) to a digital TV via an HDMI cable. My understanding is that the audio ...
Bcorngtr's user avatar
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PCM Audio file and volume

I'm working with raw pcm files(with no headers) and I was wondering, does anyone know the calculation to find the current volume of a section of sound? I have all the information on the file, such as ...
Kelly Elton's user avatar
2 votes
2 answers
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The audio of an FFmpeg converted mov file works in VLC but fails in Adobe Premiere cs5

I use this line to convert the mov file (Mark II 5D footage) to 720p: ffmpeg -i source.mov -s 1280x728 -vf crop=1280:720:0:0 -sameq -acodec copy dest_file.mov When I drag the result file to premiere,...
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1 answer
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PCM sound level resets in Ubuntu 8.04

I am using Ubuntu 8.04 and seeing that PCM volume above 75% results in very poor sound quality. So, I brought it down. But the problem is, after every reboot it resets to 100%. How can I save the PCM ...
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Converting WAV to PCM

I have WAV files and need to convert them to PCM (44,1k, 16bit, Mono) format. How can I do this from the DOS console?
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6 votes
3 answers
11k views

How to play a PCM file on an UNIX system?

I'm trying to figure out how to use libmad with C. The trouble is, libmad converts audio files to .pcm files and I'm unable to find a way to play these files. There is no straightforward .pcm player, ...
Cookie Monster's user avatar