i'm currently trying to build an access_demux module for a hardware MJPEG2000 card (no v4l).
For now, i'm just trying to read some data from the kernel-mode driver.
So basically:
1) ask the driver what the size of the frame will be (ioctl() )
2) ask VLC to give me an empty packet
3) copy the datas from the driver into the packet (read() )
He is the code (based on screen.c more or less):
Code: Select all
/*****************************************************************************
* Module descriptor
*****************************************************************************/
static int Open ( vlc_object_t * );
static void Close( vlc_object_t * );
vlc_module_begin();
set_shortname( _("Imax") );
set_description( _("Imax MJPEG2000 card") );
set_category( CAT_INPUT );
set_subcategory( SUBCAT_INPUT_ACCESS );
add_integer( "imax-caching", DEFAULT_PTS_DELAY / 1000, NULL,
CACHING_TEXT, CACHING_LONGTEXT, VLC_TRUE );
add_float( "imax-fps", IMAX_FPS, NULL, FPS_TEXT, FPS_LONGTEXT, VLC_TRUE );
add_integer( "imax-id", 0, NULL, ID_TEXT, ID_LONGTEXT, VLC_TRUE );
add_shortcut( "imax" );
set_capability( "access_demux", 10 );
set_callbacks( Open, Close );
vlc_module_end();
/*****************************************************************************
* Local prototypes
*****************************************************************************/
static int Control( demux_t *, int, va_list );
static int Demux ( demux_t * );
struct demux_sys_t
{
es_format_t fmt;
es_out_id_t *es;
float f_fps;
mtime_t i_next_date;
int i_incr;
int fd;
};
/*****************************************************************************
* DemuxOpen:
*****************************************************************************/
static int Open( vlc_object_t *p_this )
{
demux_t *p_demux = (demux_t*)p_this;
demux_sys_t *p_sys;
vlc_value_t val;
/* Fill p_demux field */
/* callbacks*/
p_demux->pf_demux = Demux;
p_demux->pf_control = Control;
p_demux->p_sys = p_sys = malloc( sizeof( demux_sys_t ) );
memset( p_sys, 0, sizeof( demux_sys_t ) );
msg_Dbg( p_demux, "opening imax access_demux");
var_Create( p_demux, "imax-caching", VLC_VAR_INTEGER|VLC_VAR_DOINHERIT );
var_Create( p_demux, "imax-fps", VLC_VAR_FLOAT|VLC_VAR_DOINHERIT );
var_Get( p_demux, "imax-fps", &val );
p_sys->f_fps = val.f_float;
p_sys->i_incr = 1000000 / val.f_float;
p_sys->i_next_date = 0;
/* open the device */
p_sys->fd = open(IMAX_DEVICE_PATH, O_RDWR);
if( p_sys->fd == -1)
{
msg_Err( p_demux, "failed to open the device");
return VLC_EGENERIC;
}
else
{
msg_Dbg( p_demux, "device %s sucessfully opened", IMAX_DEVICE_PATH);
}
#if 0
if( screen_InitCapture( p_demux ) != VLC_SUCCESS )
{
free( p_sys );
return VLC_EGENERIC;
}
msg_Dbg( p_demux, "screen width: %i, height: %i, depth: %i",
p_sys->fmt.video.i_width, p_sys->fmt.video.i_height,
p_sys->fmt.video.i_bits_per_pixel );
#endif
p_sys->es = es_out_Add( p_demux->out, &p_sys->fmt );
msg_Dbg( p_demux, "es_out_Add done, ex = %x (%d)", p_sys->es, p_sys->es);
/* es_format_Init( &p_sys->fmt, VIDEO_ES, VLC_FOURCC('m','p','2','c') ); */
/* For TS muxing, trying to make the TS muxer believe that i'm using a supported format.
This should be OK as long as I don't try to decode it ! This is only for test purpose */
es_format_Init( &p_sys->fmt, VIDEO_ES, VLC_FOURCC('M','J','P','G') );
return VLC_SUCCESS;
}
/*****************************************************************************
* Close:
*****************************************************************************/
static void Close( vlc_object_t *p_this )
{
demux_t *p_demux = (demux_t*)p_this;
demux_sys_t *p_sys = p_demux->p_sys;
#if 0
screen_CloseCapture( p_demux );
#endif
close(p_sys->fd);
free( p_sys );
}
/*****************************************************************************
* Demux:
*****************************************************************************/
static int Demux( demux_t *p_demux )
{
int i_size, ret_read;
demux_sys_t *p_sys = p_demux->p_sys;
block_t *p_block;
if( !p_sys->i_next_date ) p_sys->i_next_date = mdate();
/* Frame skipping if necessary */
while( mdate() >= p_sys->i_next_date + p_sys->i_incr )
p_sys->i_next_date += p_sys->i_incr;
mwait( p_sys->i_next_date );
msg_Dbg( p_demux, "preparing for ioctl, fd=%d", p_sys->fd);
i_size = ioctl( p_sys->fd, VJ2C_READSIZE, 0);
/* allocating the new block */
msg_Dbg( p_demux, "preparing for block_New, i_size=%d", i_size);
if( !( p_block = block_New( p_demux, i_size ) ) )
{
msg_Err( p_demux, "cannot get block, p_block=%x", p_block );
}
else
{
/* effectively reading data */
ret_read=read(p_sys->fd, p_block->p_buffer, i_size);
if (ret_read == -1)
{
msg_Err( p_demux, "failed to read frame");
free (p_block);
p_block = NULL;
}
else
{
msg_Dbg( p_demux, "Everything is fine, block created", p_sys->fd);
}
}
if( !p_block )
{
/* allocation failed */
p_sys->i_next_date += p_sys->i_incr;
return 1;
}
p_block->i_dts = p_block->i_pts = p_sys->i_next_date;
msg_Dbg( p_demux, "Finished. p_block=%p, date=%lld", p_block, p_block->i_dts );
es_out_Control( p_demux->out, ES_OUT_SET_PCR, p_block->i_pts );
es_out_Send( p_demux->out, p_sys->es, p_block );
p_sys->i_next_date += p_sys->i_incr;
return 1;
}
/*****************************************************************************
* Control:
*****************************************************************************/
static int Control( demux_t *p_demux, int i_query, va_list args )
{
vlc_bool_t *pb;
int64_t *pi64;
switch( i_query )
{
/* Special for access_demux */
case DEMUX_CAN_PAUSE:
case DEMUX_CAN_CONTROL_PACE:
/* TODO */
pb = (vlc_bool_t*)va_arg( args, vlc_bool_t * );
*pb = VLC_FALSE;
return VLC_SUCCESS;
case DEMUX_GET_PTS_DELAY:
pi64 = (int64_t*)va_arg( args, int64_t * );
*pi64 = (int64_t)var_GetInteger( p_demux, "imax-caching" ) *1000;
return VLC_SUCCESS;
/* TODO implement others */
default:
return VLC_EGENERIC;
}
}
It seems to work: ioctl read the correct size, the packet is created and the data are copied.
In the end, i have an address for the packet (different each time) and a DTS, the delta between the DTS being 100000 si 1 sec so it is great.
I can't decode (unsupported format + 120 Mhz ARM
) so i tested it with --vout dummy. It looks fine: no error. and 1 packet each second.Then, i decided to try sout/std/file/ts since in the end the aim is sout/std/udp/ts. I have the debug message, 1 packet per second, etc and the data is... 0 bytes large :-/
The very same parameters for sout work perfectly with an AVI MJPEG file so they are not the main problem.
Does anyone here has any idea ? Any clues about the API ? The only info I have is an old mail from fenrir in the ml and of course the beloved source code but honnestly it's incredibly hard for me to understand "the way it works" so the only solution is to look at my neighbor (screen.c in this case) like we all do/did at school but hmmm it's not that great when you need to do a little different :-/
