Audio 5.1

Dolby Digital

• http://en.wikipedia.org/wiki/Dolby_Digital

DTS

• http://pt.wikipedia.org/wiki/DTS

Som surround

• http://eletronicos.hsw.uol.com.br/som-surround.htm

Projetos de aplicativos de filtros para formato ac3

• http://ac3filter.net/projects

• Configurando alsa, ~/.asoundrc:

pcm.!default {
type plug
slave.pcm "surround51"
slave.channels 6
route_policy duplicate
}

• retirado de http://linux.p2pforum.it/wiki/Hardware_supportato#Abilitare_l.27audio_5.1

configurando arquivo no formato ac3 com multicanal (de 1 para 5)

com ffmpeg:

ffmpeg -i l.wav -i r.wav -i sl.wav -i sr.wav -i c.wav -ab 192k -ar \
48000 -ac 5 -acodec ac3 -y surround.ac3

aften

criando áudio com soundround 5.1

• pagina do projeto

http://aften.sourceforge.net/

• dica de uso

http://parumi.wordpress.com/2007/12/12/how-to-create-multichannel-51-ac3-audio-and-video-in-linux/

$ apt-cache show aften

Description: audio AC3 encoder
Aften is an audio encoder which generates compressed audio streams based on
ATSC A/52 specification. This type of audio is also known as AC-3 or Dolby®
Digital and is one of the audio codecs used in DVD-Video content.
Bugs: mailto:marillat@debian.org
Homepage: http://aften.sourceforge.net/

usando:

sox -M L.wav R.wav C.wav SL.wav SR.wav surround.wav
aften -b 448 -cmix 0 -smix 0 -dsur 2 -acmod 7 surround.wav surround.ac3

sobre os parâmetros usados acima:

• -b 448 — Bitrate in kbps (4 channels: 384 kbps, 5 channels: 448 kbps)
• -smix 2 — Surround mix level ( 0: -3dB, 1: -6dB, 2: 0 )
• -dsur 2 — (2: Dolby surround encoded, 0: not indicated, 1: not Dolby surround encoded)
• -acmod 7 — Audio coding mode, or channel order (7: L,R,C,SL,SR)

com mplayer.

mencoder -ovc copy video.avi -audiofile surround.ac3 -oac copy -o newvideo.avi

assistindo em mplayer com 6 canais, usando jack

mplayer newvideo.avi -ao jack -channels 6
mplayer -ao jack -channels 5 surround.wav

somente alsa:

mplayer -channels 6 -ao alsa:mmap:noblock:device=hw=0.1  dvd://4

• retirado de How to create multichannel (5.1) AC3 audio (and video) in Linux

Mais sobre audio 5.1 no computador

• http://www.hardwaresecrets.com/article/268

Surround Sound

• http://alsa.opensrc.org/index.php/SurroundSound

• How to set up surround 5.1 audio in Linux with Alsa