[vlc-devel] [PATCH 2/2] Add a simple raw hevc demux

[Vittorio Giovara]

Hi Denia

On Tuesday, February 11, 2014, Denis Charmet <typx at dinauz.org> wrote:

> ---
>  modules/demux/Makefile.am |   3 +
>  modules/demux/mpeg/hevc.c | 349
> ++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 352 insertions(+)
>  create mode 100644 modules/demux/mpeg/hevc.c
>
>
> +
> +
> +static void skipProfileTiersLevel( bs_t * bs, int32_t
> max_sub_layer_minus1 )
> +{
> +    uint8_t sub_layer_profile_present_flag[8];
> +    uint8_t sub_layer_level_present_flag[8];
> +
> +    /* skipping useless fields of the VPS see
> https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-H.265-201304-I!!PDF-E&type=item*/
> +    bs_skip( bs, 2 + 1 + 5 + 32 + 1 + 1 + 1 + 1 + 44 + 8 );
> +
> +    for( int32_t i = 0; i < max_sub_layer_minus1; i++ )


Shouldn't this be <= ?


> +    {
> +        sub_layer_profile_present_flag[i] = bs_read1( bs );
> +        sub_layer_level_present_flag[i] = bs_read1( bs );
> +    }
> +
> +    if(max_sub_layer_minus1 > 0)
> +        bs_skip( bs, (8 - max_sub_layer_minus1) * 2 );
> +
> +    for( int32_t i = 0; i < max_sub_layer_minus1; i++ )


Ditto


> +    {
> +        if( sub_layer_profile_present_flag[i] )
> +            bs_skip( bs, 2 + 1 + 5 + 32 + 1 + 1 + 1 + 1 + 44 );
> +        if( sub_layer_level_present_flag[i] )
> +            bs_skip( bs, 8 );
> +    }
> +}
> +
> +static uint32_t read_ue( bs_t * bs )
> +{
> +    int32_t i = 0;
> +
> +    while( bs_read1( bs ) == 0 && bs->p < bs->p_end && i < 32 )
> +        i++;
> +
> +    return (1 << i) - 1 + bs_read( bs, i );
> +}
> +
> +static int32_t getFPS( demux_t *p_demux, block_t * p_block )
> +{
> +    demux_sys_t *p_sys = p_demux->p_sys;
> +
> +    bs_t bs;
> +    uint8_t * p_decoded_nal;
> +    int i_decoded_nal;
> +
> +    if( p_block->i_buffer < 5 )
> +        return -1;
> +
> +    CreateDecodedNAL( &p_decoded_nal, &i_decoded_nal,
> +                              p_block->p_buffer+3, p_block->i_buffer-3 );
> +
> +    if( !p_decoded_nal )
> +        return -1;
> +
> +    bs_init( &bs, p_decoded_nal, i_decoded_nal );
> +    bs_skip( &bs, 12 );
> +    int32_t max_sub_layer_minus1 = bs_read( &bs, 3 );


IMHO I find it clearer when the _minus1 is dropped from the variable and +1
is summed to it, especially if you have to loop on them (but that's just a
personal opinion)


> +    bs_skip( &bs, 17 );
> +
> +    skipProfileTiersLevel( &bs, max_sub_layer_minus1 );
> +
> +    int32_t vps_sub_layer_ordering_info_present_flag = bs_read1( &bs );
> +    int32_t i = vps_sub_layer_ordering_info_present_flag? 0 :
> max_sub_layer_minus1;
> +    for( ; i <= max_sub_layer_minus1; i++ )


Slightly hard to read, wouldn't a plain
if (vps_sub_layer_ordering_info_present_flag)
be just as effective?

Vittorio

+    {
> +        read_ue( &bs );
> +        read_ue( &bs );
> +        read_ue( &bs );
> +    }
> +    uint32_t vps_max_layer_id = bs_read( &bs, 6);
> +    uint32_t vps_num_layer_sets_minus1 = read_ue( &bs );
> +    bs_skip( &bs, vps_max_layer_id * vps_num_layer_sets_minus1 );
> +
> +    if( bs_read1( &bs ))
> +    {
> +        uint32_t num_units_in_tick = bs_read( &bs, 32 );
> +        uint32_t time_scale = bs_read( &bs, 32 );
> +        if( num_units_in_tick )
> +        {
> +            p_sys->f_fps = ( (float) time_scale )/( (float)
> num_units_in_tick );
> +            msg_Dbg(p_demux,"Using framerate %f fps from VPS",
> p_sys->f_fps);
> +        }
> +        else
> +        {
> +            msg_Err( p_demux, "vps_num_units_in_tick null defaulting to
> 25 fps");
> +            p_sys->f_fps = 25.0f;
> +        }
> +    }
> +    else
> +    {
> +        msg_Err( p_demux, "No timing info in VPS defaulting to 25 fps");
> +        p_sys->f_fps = 25.0f;
> +    }
> +    free(p_decoded_nal);
> +    return 0;
> +}
> --
> 1.9.rc1
>
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