h264.cpp

linux下实现视频播放的播放器

/*
 *  Copyright (C) 2007  gulikoza
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/* $Id$ */

#include "iptv.h"

#include "h264.h"

//#define DEBUG
#define MODULE "h264"

#include "log.h"

class h264reader
{
private:
    int bits;
    int size;
    int read;
    unsigned char * pkt;

public:
    h264reader(unsigned char * p, int offset, int s):bits(8),size(s-offset),read(0)
    {
	pkt = p+offset;
	DEBUG_MSG("Starting bytes: 0x%x 0x%x 0x%x", pkt[0], pkt[1], pkt[2]);
    }

    unsigned int GetBits(int num)
    {
	if(num == 0) {
	    LOG_MSG("Requested 0 bits");
	    return 0;
	}

	if(num > 32) {
	    LOG_MSG("Requested too many (%d) bits", num);
	    return 0;
	}

	if(bits == 0) {
	    if(size == 0) {
		LOG_MSG("Unexpected end of packet!");
		return 0;
	    }
	    bits = 8;
	    size--;
	    pkt++;
	    read++;

	    // Emulation prevention byte
	    if((pkt[0] == 0x3) && (read > 2) && (pkt[-1] == 0x0) && (pkt[-2] == 0x0)) {
		size--;
		pkt++;
	    }
	}

	int use = (num>bits) ? bits:num;

	// Get bits from current byte
	unsigned int ret = (pkt[0]>>(bits-use)) & ((0x1<<use)-1);
	bits -= use;

	DEBUG_MSG("Bits to be used: %d, value 0x%x", use, ret);
	if(num-use == 0)
	    return ret;

	return ((ret<<(num-use))|GetBits(num-use));
    }

    unsigned int Get_UEG()
    {
	int bits = 0;

	while(GetBits(1) == 0)
	    bits++;

	DEBUG_MSG("Exp-Golomb length: %d", bits);
	if(bits == 0)
	    return 0;

	unsigned int ret = ((0x1<<bits)|GetBits(bits))-1;
	DEBUG_MSG("Exp-Golomb read: %d", ret);
	return ret;
    }

    int Get_SEG()
    {
	int num = Get_UEG();

	if(num == 0)
	    return num;

	if(num % 2 == 0)
	    num = num / (-2);
	else
	    num = (num + 1) / 2;

	DEBUG_MSG("Signed Exp-Golomb returned %d", num);
	return num;
    }
};

int h264findnal_type(unsigned char * pkt, unsigned int size, int type)
{
    unsigned int ndx = 0;

    while(ndx < (size - 3)) {
	if(pkt[ndx] < 0x2) {

	    if((pkt[ndx] == 0x1) && (ndx > 2))
		ndx -= 3;
	    else if((pkt[ndx+1] == 0x1) && (ndx > 1))
		ndx -= 2;
	    else if((pkt[ndx+2] == 0x1) && (ndx > 0))
		ndx -= 1;

	    unsigned int nal = pkt[ndx]<<24 | pkt[ndx+1]<<16 | pkt[ndx+2]<<8 | pkt[ndx+3];

	    if(nal != 0x1) {
		ndx += 4;
		continue;
	    }

	    // NAL starts after the separator
	    ndx += 4;

	    if(pkt[ndx]&0x80) {
		ndx += 4;
		LOG_MSG("Forbidden NAL bit set!");
		continue;
	    }

	    int t = (pkt[ndx]&0x1F);
	    LOG_MSG("Found NAL unit: ID 0x%x, type 0x%x @ %d", (pkt[ndx]&0x60)>>5, t, ndx);

	    if(t == type)
		return ndx+1;
	}
	ndx += 4;
    }

    return -1;
}

// Sequence parameter set is in NAL unit type 0x7
int h264parse_seq(h264info * info)
{
    h264reader * stream = new h264reader(info->pkt, info->offset, info->size);

    int profile_idc = stream->GetBits(8);
    LOG_MSG("Profile_idc: %d", profile_idc);

    // Skip constraint...
    stream->GetBits(16);

    // Seq_id
    stream->Get_UEG();

    // High-profile has additional info?
    if(profile_idc >= 100) {
	if(stream->Get_UEG() == 3) // chroma_format_idc
	    stream->GetBits(1);	   // residual_color_transform_flag
	stream->Get_UEG();	   // bit_depth_luma_minus8
	stream->Get_UEG();	   // bit_depth_chroma_minus8
	stream->GetBits(1);
	// Scaling matrix
	if(stream->GetBits(1)) {
	    LOG_MSG("Scaling matrix is present");
	    for(unsigned int i = 0; i < 8; i++) {
		if(stream->GetBits(1)) {
		    int next = 8, last = 8;
		    for(unsigned int j = (i>6 ? 64:16); j; j--) {
			if(next)
			    next = (last + stream->Get_SEG()) & 0xff;
			last = next ? next : last;
		    }
		}
	    }
	}
    }

    // log2_max_frame_num_minus4
    stream->Get_UEG();

    // pic_order_cnt_type
    profile_idc = stream->Get_UEG();

    if(profile_idc == 0) {
	LOG_MSG("Pic_order_cnt_type == 0");
	stream->Get_UEG();
    } else if(profile_idc == 1) {
	LOG_MSG("Pic_order_cnt_type == 1");
	stream->GetBits(1);
	stream->Get_UEG();
	stream->Get_UEG();

	for(unsigned int i = stream->Get_UEG(); i; i--)
	    stream->Get_UEG();
    }

    stream->Get_UEG();
    stream->GetBits(1);

    // Finally what we want...
    info->width = (stream->Get_UEG() + 1) * 16;
    info->height = (stream->Get_UEG() + 1) * 16;

    if(!stream->GetBits(1)) {
	// Interlaced...
	info->height *= 2;
	stream->GetBits(1);
    }
    LOG_MSG("Got picture parameters: %dx%d", info->width, info->height);

    stream->GetBits(1);
    if(stream->GetBits(1)) {
	stream->Get_UEG();
	stream->Get_UEG();
	stream->Get_UEG();
	stream->Get_UEG();
    }

    // Hopefully VUI is also present...
    info->aspect = 0.0;
    info->frame_time = 0.0;
    if(stream->GetBits(1)) {
	if(stream->GetBits(1)) {
	    switch(stream->GetBits(8)) {
		case 1: info->aspect = 1.0;
		    break;
		case 2: info->aspect = 12.0/11.0;
		    break;
		case 3: info->aspect = 10.0/11.0;
		    break;
		case 4: info->aspect = 16.0/11.0;
		    break;
		case 5: info->aspect = 40.0/33.0;
		    break;
		case 6: info->aspect = 24.0/11.0;
		    break;
		case 7: info->aspect = 20.0/11.0;
		    break;
		case 8: info->aspect = 32.0/11.0;
		    break;
		case 9: info->aspect = 80.0/33.0;
		    break;
		case 10: info->aspect = 18.0/11.0;
		    break;
		case 11: info->aspect = 15.0/11.0;
		    break;
		case 12: info->aspect = 64.0/33.0;
		    break;
		case 13: info->aspect = 160.0/99.0;
		    break;
		case 255:
		    info->aspect  = (double)stream->GetBits(16);
		    info->aspect /= (double)stream->GetBits(16);
		    break;
		default:
		    LOG_MSG("AR not specified!");
	    }
	}
	LOG_MSG("VUI parameters present, AR: %.2f", info->aspect);

	// Overscan
	if(stream->GetBits(1))
	    stream->GetBits(1);

	// Video info
	if(stream->GetBits(1)) {
	    stream->GetBits(3);
	    stream->GetBits(1);
	    if(stream->GetBits(1)) {
		stream->GetBits(8);
		stream->GetBits(8);
		stream->GetBits(8);
	    }
	}

	if(stream->GetBits(1)) {
	    stream->Get_UEG();
	    stream->Get_UEG();
	}

	if(stream->GetBits(1)) {
	    info->frame_time  = stream->GetBits(32) * 2000;
	    info->frame_time /= stream->GetBits(32);
	    LOG_MSG("Timing info present: %.2f", info->frame_time);
	}
    }

    // Already done? :-)
    delete stream;
    return 0;
}