[MPlayer-dev-eng] playing AC3 through HDMI abnormal sound issue

[AnnieLiu at viatech.com.cn]

Dear All

 

I am Annie Liu from VIA Technology. I met an issue when play ac3 through HDMI by mplayer and need your help.

 

I added the codec patch into alsa-driver to support our HDMI audio and I declared it as “HDA_PCM_TYPE_HDMI”. It works fine when play wav file.

 

Now, I met an issue when playing audio with AC3 format through HDMI. 

 

If I use VLC (A52->S/PDIF), the sound is Okay, and the audio format displayed on amplifier is “D” (Dolby) as well. But I use mplayer with option “-ac hwac3”, the audio sounds abnormal, although the amplifier display “D” (Dolby). I tried mplayer with “-ac a52”, but I found it decode AC3 to PCM.

 

On the contrary, if I try “-ac hwac3” on a “digital codec” in our SB which declared as “HDA_PCM_TYPE_SPDIF”, the sound is fine; but if I use VLC (A52->S/PDIF) no sound outputted. 

In VLC, I also found some a52 libraries:

/usr/lib/vlc/plugins/codec/liba52_plugin.so

/usr/lib/vlc/plugins/audio_filter/liba52tospdif_plugin.so

 

I wonder how I can play ac3 by mplayer through HDMI in Dolby?

 

I tried to declare my HDMI as “HDA_PCM_TYPE_SPDIF” in codec patch, the abnormal issue happened as well. (Playing PCM is Okay).

I wonder if the audio data encoded by hwac3 is compatible with HDMI.

 

I searched a lot of topics related to playing ac3 through HDMI, and found someone said I should set AES0 as 0x02. I did it by iecset, it works. But when I play ac3 by mplayer, it always reports “[AO-ALSA] alsa-lib: pcm.c:2208: (snd_pcm_open_noupdate) Unknown PCM hw:0,3,AES0=6”. I don’t know why it happens. 

 

Could anyone give me favor on it?

Thanks a lot in advance!

 

Thanks a lot.

BR//Annie

 

 

 

Annie Liu （刘晓丽） 
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Software Team, 5th Floor, VIA Technologies (China) Inc., Ltd. 

VIA Building, Tsinghua Science Park building No.7 No.1 

Zhongguancun East Road, Haidian District, Beijing, 

100084 

Tel: 86-10-59852288 ext. 3865 
E-mail: annieliu at viatech.com.cn <blocked::mailto:annieliu at viatech.com.cn> 

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