Hi Navin,
You don't need RGB for bitmap. AFAIK BMP pictures can also embed YUV4:2:0
Here is a h264 decoding code that works fine. It may help you extracting the
right parts.
//#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"
#include "avcodec/avcodec.h"
static int FindStartCode (unsigned char *Buf, int zeros_in_startcode)
{
int info;
int i;
info = 1;
for (i = 0; i < zeros_in_startcode; i++)
if(Buf[i] != 0)
info = 0;
if(Buf[i] != 1)
info = 0;
return info;
}
int getNextNal(FILE* inpf, unsigned char* Buf)
{
int pos = 0;
while(!feof(inpf) && (Buf[pos++]=fgetc(inpf))==0);
int StartCodeFound = 0;
int info2 = 0;
int info3 = 0;
while (!StartCodeFound)
{
if (feof (inpf))
{
return -1;
}
Buf[pos++] = fgetc (inpf);
info3 = FindStartCode(&Buf[pos-4], 3);
if(info3 != 1)
info2 = FindStartCode(&Buf[pos-3], 2);
StartCodeFound = (info2 == 1 || info3 == 1);
}
fseek (inpf, -4, SEEK_CUR);
return pos - 4;
}
int main()
{
int i;
FILE * inpf;
FILE * outf;
inpf = fopen("test.264", "rb");
outf = fopen("out1_720x576.yuv", "wb");
int nalLen = 0;
unsigned char* Buf = (unsigned char*)calloc ( 1000000, sizeof(char));
unsigned char* Buf1 = (unsigned char*)calloc ( 1000000, sizeof(char));
int width = 720;
int height = 576;
//unsigned char yuvData[352 * 240 * 3];
AVCodec *codec; // Codec
AVCodecContext *c; // Codec Context
AVFrame *picture; // Frame
avcodec_init();
avcodec_register_all();
codec = avcodec_find_decoder(CODEC_ID_H264);
if (!codec) {
return 0;
}
//allocate codec context
c = avcodec_alloc_context();
if(!c){
return 0;
}
//open codec
if (avcodec_open(c, codec) < 0) {
return 0;
}
//allocate frame buffer
picture = avcodec_alloc_frame();
if(!picture){
return 0;
}
while(!feof(inpf))
{
//printf("cntr: %d\n", cntr++);
nalLen = getNextNal(inpf, Buf);
//try to decode this frame
int got_picture, result;
result= avcodec_decode_video(c, picture, &got_picture, Buf,
nalLen);
if(result > 0)
{
//fwrite(picture->data[0],1,width*height,outf);
//fwrite(picture->data[1],1,width*height/4,outf);
//fwrite(picture->data[2],1,width*height/4,outf);
#if 0 //this is also ok!
for(i=0; i<c->height; i++)
fwrite(picture->data[0] + i *
picture->linesize[0], 1, c->width, outf );
for(i=0; i<c->height/2; i++)
fwrite(picture->data[1] + i *
picture->linesize[1], 1, c->width/2, outf );
for(i=0; i<c->height/2; i++)
fwrite(picture->data[2] + i *
picture->linesize[2], 1, c->width/2, outf );
#endif
//http://ffmpeg.org/doxygen/trunk/group__lavc__picture.html#g99bc554a84681f7ee6422a384007a4ca
//Copy pixel data from an AVPicture into a buffer,
always assume a linesize alignment of 1.
avpicture_layout((AVPicture *)picture, c->pix_fmt,
c->width, c->height, Buf1, c->width*c->height*1.5);
fwrite(Buf1, c->width*c->height*1.5, 1, outf);
}
}
if(c) {
avcodec_close(c);
av_free(c);
c = NULL;
}
if(picture) {
av_free(picture);
picture = NULL;
}
return 1;
}
Malik,
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Navin
Sent: 20 November 2012 09:49
To: [email protected]
Subject: Re: [Libav-user] get RGB values from ffmpeg frame
Been trying these techniques, but I keep getting crashes. Help please?:
avpicture_fill((AVPicture*) frame2, frame2_buffer, PIX_FMT_RGB24,
width2, height2);
//printf("data = %d, %d, %d, %d
\n",frame2->data[0],frame2->data[1],frame2->data[2],frame2->data[3]);
//printf("linesize = %d %d %d\n",frame2->linesize[0],
frame2->linesize[1], frame2->linesize[2]);
//printf("width = %d\n", pCodecCtx->width);
//printf("height = %d\n", pCodecCtx->height);
//std::cin.get();
int linesize = frame2->linesize[0];
for(int xx = 0; xx < (linesize * width1)-1; xx += 3)
{
int r = frame2->data[0][xx];//int r = frame2->data[0][xx];
int g = frame2->data[0][xx+1];
int b = frame2->data[0][xx+2];
printf("xx=%d r=%d, g=%d, b=%d \n",xx, r,
g, b);
}
printf("frame%d done----------------",i++);
//for(int xx = 0; xx < width1; xx = xx + 3)
//{
// for(int yy = 0; yy < height1; ++yy)
// {
// //int p = xx*3 + yy*frame2->linesize[0];
// //int p = xx * 3 + yy * linesize;
// printf("yy=%d xx=%d",yy,xx);
// int p = yy * linesize + xx;
// printf("p=%d\n",p);
// int r = frame2->data[0][p];
// int g = frame2->data[0][p+1];
// int b = frame2->data[0][p+2];
// printf("[r=%d, g=%d, b=%d ]\n", r, g, b);
// }//for
//}//for
Nav
On 11/20/2012 8:52 AM, Nav wrote:
> Hi! Glad to be part of this mailing list.
> What I wanted to create, was a program which would receive a streaming
> video, and when it decodes a frame of the video into either a bitmap
> format or just pure RGB (perhaps stored in a char array), it would
> notify another program that it has received a frame, and the other
> program would take the RGB values and display it.
> I've already asked this question here:
> http://ffmpeg.zeranoe.com/forum/viewtopic.php?f=15&t=805
> and rogerdpack told me to post my question on the libav mailing list.
> I have been through many websites, but they either use img_convert
> (which doesn't work) or sws_scale, which crashes when I try to use it
> with RGB.
> Could anyone help with a complete piece of code which can give me the
> RGB values of a frame?
>
> This is a part of the YUV conversion that I tried initially.
>
> i=0;
> while(av_read_frame(pFormatCtx, &packet) >= 0)
> {
> // Is this a packet from the video stream?
> if(packet.stream_index==videoStream)
> {
> // Decode video frame
> avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
>
> // Did we get a video frame?
> if(frameFinished)
> {
> // Convert the image into YUV format that SDL uses
> sws_scale( sws_ctx, (uint8_t const * const *)pFrame->data,
> pFrame->linesize, 0, pCodecCtx->height, pict.data, pict.linesize );
>
>
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http://ffmpeg.org/mailman/listinfo/libav-user
