[vlc-devel] [PATCH] New mpg123 decoder

[Felix Paul Kühne]

Hey Ludo,

three remarks, two inlined.

1) When starting playback, the first buffer I hear from my speaker is a strong static noise. Afterwards, playback is fine. Can you check that?

> On 25 Nov 2014, at 17:57, Ludovic Fauvet <etix at videolan.org> wrote:
> 
> ---
> NEWS                      |   1 +
> configure.ac              |   5 +
> modules/MODULES_LIST      |   1 +
> modules/codec/Makefile.am |   7 +
> modules/codec/mpg123.c    | 318 ++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 332 insertions(+)
> create mode 100644 modules/codec/mpg123.c
> 
> diff --git a/NEWS b/NEWS
> index d109573..1ef4da7 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -20,6 +20,7 @@ Decoder:
>  * Important improvements for the MMAL decoder and output for rPI
>  * Support HEVC hardware decoding using OMX and MediaCodec
>  * Support VP9 and WMV3 decoding using OMX and performance improvements
> + * New MPEG-1 & 2 audio layer I, II, III + MPEG 2.5 decoder

2) .. “based on libmpg123"

> +/****************************************************************************
> + * DecodeBlock: the whole thing
> + ****************************************************************************/
> +static block_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
> +{

[snip]

> +    /* Configure the output */
> +    p_dec->fmt_out.audio.i_frame_length = p_block->i_nb_samples = mpg123_spf( p_sys->p_handle );
> +    p_dec->fmt_out.audio.i_bytes_per_frame = mpg123_outblock( p_sys->p_handle );
> +    p_dec->fmt_out.i_bitrate = p_sys->frame_info.bitrate * 1000;
> +
> +    switch( p_sys->frame_info.mode )
> +    {
> +        case MPG123_M_STEREO:
> +        case MPG123_M_JOINT:
> +            p_dec->fmt_out.audio.i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
> +            break;
> +        case MPG123_M_DUAL:
> +            p_dec->fmt_out.audio.i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
> +                                | AOUT_CHAN_DUALMONO;
> +            break;
> +        case MPG123_M_MONO:
> +            p_dec->fmt_out.audio.i_original_channels = AOUT_CHAN_CENTER;
> +            break;
> +        default:
> +            msg_Err( p_dec, "Unknown mode");
> +            block_Release( p_block );
> +            return NULL;
> +    }
> +
> +    p_dec->fmt_out.audio.i_physical_channels =
> +        p_dec->fmt_out.audio.i_original_channels & AOUT_CHAN_PHYSMASK;

I might miss something obvious here, but are you sure that you need to set this info for every single packet you decode?

Cheers,

Felix