Re: [libdv-dev] Image Processing using Firewire

[Dan D. <da...@de...>]

First, it is not a good idea to decode inside the libraw1394 receive
handler. You want to return this memory to the DMA engine of the OHCI
controller as soon as possible. Secondly, the only way I have ever used
libdv is by supplying it all of the DV for a frame at one time. For
NTSC, 250 DV blocks are supplied per frame and 300 for PAL with each
block being 480 bytes. If you look at the value of the length parameter
in the receive handler you should see that it is 496 when it is not 16.
So, you can not just copy 120000 or 144000 bytes out the data pointer.
Also make sure the first packet in the dv buffer is the first block of
the frame. See dvconnect or playdv source code for how to detect the
beginning of frame.

On Thu, 2005-03-10 at 13:38 -0800, Juan Cantonez wrote:
> Hi,
> 
> I have a Sony VX2000 DV camera which supports firewire
> connection. What I would like to do is capture frames
> continuously from the firewire and save those frames
> to my hard disk for image processing. After some
> research, I found that to capture the raw DV data
> libraw1394 library in linux has to be used and to
> decode the data libdv should be used. I wrote a small
> code for this purpose, however I am getting weird,
> random colored images. I also looked at the examples
> that come from libdv source files; however no luck at
> all. Can somebody please look at my code and tell me
> what I am doing wrong? I got stuck on this and I can't
> start my research area. Thanks a lot for your
> responses in advance. Here is my code: 
> 
> #define BUFFER 1000
> #define PACKET_MAX 4096
> 
> #include <iostream>
> #include
> "/home/elgitaro/libraw1394-1.1.0/src/raw1394.h"
> #include <libdv/dv.h>
> using namespace std;
> u_int64_t listen_channels;
> raw1394handle_t handle;
> int num_of_cards;
> struct raw1394_portinfo pinf[ 16 ];
> quadlet_t buffer;
> dv_decoder_t *mydecoder;
> raw1394_iso_dma_recv_mode mode;	
> int pitches[3];
> unsigned char *pixels[1];
> char filename[1024];
> void saveasppm(unsigned char**,dv_decoder_t);
> unsigned char dv_buffer[144000];
> unsigned char video_buffer[720 * 576 * 3];
> int *isPAL = FALSE;
> 
> 
> static enum raw1394_iso_disposition 
> iso_handler(raw1394handle_t handle, unsigned char
> *data, 
>         unsigned int length, unsigned char channel,
>         unsigned char tag, unsigned char sy, unsigned
> int cycle, 
>         unsigned int dropped)
> {
> 	if ( length > 16 )
> 	{
> 		memcpy(dv_buffer,data,120000);
> 		unsigned char * p = ( unsigned char* ) & data[ 3 ];
>         if (p[ 3 ] & 0x80) { //Check if the signal is
> PAL
> 				cout << "Pal" << endl;
> 				mydecoder->clamp_luma = FALSE;
> 				mydecoder->clamp_chroma = FALSE;
> 				dv_reconfigure(FALSE, FALSE);
>                 memcpy(dv_buffer + 120000, data,
> 144000 - 120000);
> 		}
> 		if((dv_parse_header(mydecoder, dv_buffer)) < 0){
>       	cout << "dv_parse_header failed" << endl;
> 		return RAW1394_ISO_OK;	
>     }
> 		else
> 			cout << "Parse Header successful" << endl; 
> 	
> 	pitches[0] = 720 * 3; //mydecoder->width * 3;
> 	//dv_parse_packs (mydecoder, dv_buffer);
>     dv_decode_full_frame(mydecoder,
> 			 dv_buffer,
> 			 e_dv_color_rgb, /* RGB */
> 			 pixels,
> 			 pitches);
> 	FILE *fp;
> 	sprintf(filename, "outbuf.ppm");
>     fp = fopen(filename, "wb");
>     if(fp != NULL)
> 		{
>       fprintf(fp, "P6\n%d
> %d\n255\n",mydecoder->width,mydecoder->height);
>       fwrite(pixels[0], 1,
> 3*mydecoder->width*mydecoder->height, fp);
>       fclose(fp);	
> 		}
> 	 }	
> 	return RAW1394_ISO_OK;
> }
> 
> int main()
> {
> 	pixels[0] = video_buffer;
> 	handle = raw1394_new_handle();
> 	if (handle==0)
> 		cout << "No handle has been created" << endl;
> 	else
> 		cout << "Handle is: " << handle << endl;
> 	//num_of_cards = raw1394_get_port_info( handle, pinf,
> 16 );
> 	//cout << "Number of ports: " << num_of_cards <<
> endl;
> 	//cout << "Port info: " << pinf[0].name << " . " <<
> pinf[0].nodes << endl;
> 		if (raw1394_set_port(handle, 0) < 0) 
> 			{
> 				cout << "Couldn't set port";
> 				exit(1);
> 		}
> 	mode = RAW1394_DMA_DEFAULT;
> 		
> 	raw1394_iso_multichannel_recv_init(handle,
> iso_handler,
>                         BUFFER, 2048, -1);
> 		listen_channels = ~0ULL;
> 		raw1394_iso_recv_set_channel_mask(handle,
> listen_channels);
> 		
> 	
> 	 
> 	/* create dv decoder */
> 	cout << "creating the dv decoder" << endl; 
>   	mydecoder = dv_decoder_new(FALSE, FALSE, FALSE);
> 	if(mydecoder == NULL)
>     	cout << "dv_decoder_new failed" << endl;
> 	mydecoder->video->arg_monochrome = 0; /* color frames
> */
>   	mydecoder->quality = 
>     mydecoder->video->quality = DV_QUALITY_BEST; /*
> color and fine scale */
> 
> 
> 
> 	
> 	if(raw1394_iso_recv_start(handle, -1, -1, 0)==0)
> 		cout << "iso_recv_start success" << endl;
>     //while (raw1394_loop_iterate(handle) == 0);
> 	//for (int i=0; i<5; i++)
> 	raw1394_loop_iterate(handle);
> 	
> 	
> 	dv_decoder_free(mydecoder);
> 	raw1394_iso_shutdown(handle);
> 	exit(1);		
> }
> 
> 
> 
> 		
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