Android下基于Http协议的网络摄像机开发
这段时间在做Android平台下的网络摄像机的兼容，摄像机的通讯采用Http1.1协议。现将遇到的问题简单总结一下：
1. Http协议中需要用到身份认证部分,不同厂家的摄像机所采取的方案可能有所不同，但是大体无外乎都是将摄像机的用户名和密码简单的用Base64加密转换后封装成特定字段反馈给摄像机，摄像机对接收到的加密字段进行匹配。常见的方法是：Base64（用户名：密码）（将用户名和密码用‘：’连接，然后对其进行Base64转换）。
2. 视频数据传输一般是采用Rtsp实时数据流传输协议，对Rtsp数据流进行拆包组帧转换为H264数据帧成了首要解决的问题。这个过程可以放在Android上层用Java实现，也可以放到JNI底层实现。本人最初在上层用Java实现了Rtsp的拆包组帧，最后在实际的运行当中发现：低分辨率的摄像机可以勉强运行，一旦连接高分辨率的摄像机就会出现丢帧和花屏的现象。最后不得不将该模块用C重写封装成接口放到底层，运行1280*720分辨率都很流畅。总结：Java实现数据转换的效率不高，最好放到JNI底层来实现复杂的数据运算。
3. H264解码器的问题。最初是从网上下载了一个经过裁剪的H264解码器（基于FFMPEG开源项目）。在测试中发现有时候会出现底层解码错误导致整个程序崩溃，这个问题困扰了我们很久。最后决定移植一个完整的ffmpeg解码器来解决这个问题，网上有众多网友做过相关的事情。经过漫长的接口封装调试最终成功解决。从1280*720、640*360、到320*240分辨率的测试
都很流畅（Android.mk、JNI接口文件，解码器源码等相关代码将上传到资源）
项目中后来用到的解码器为ffmpeg1.2版本，通过移植其H264视频解码模块来满足了应用项目的要求，下面贴上Jni接口的C源码：
#include
#include
#include
#include
#include
#include
#include "ffmpeg/libavformat/avformat.h"
#include "ffmpeg/libavcodec/avcodec.h"
#include "ffmpeg/libswscale/swscale.h"
////////////////////////////////
AVCodec *m_pCodec = NULL;
AVCodecContext *m_pCodecCtx = NULL;
AVFrame *m_pFrame = NULL;
struct SwsContext *pSwsCtx = NULL;
AVPacket m_packet;
int m_width = 0;
int m_height = 0;
const int MAX_VIDEO_W = 1280;
const int MAX_VIDEO_H = 720;
static int g_bInit = 0;
int g_iFrame = 0;
//picture
char *fill_buffer;
AVFrame *frame_rgb;
struct SwsContext *img_convert_ctx;
jboolean bPicture = JNI_FALSE;
///////////////////////////////
#define MAX_RGB_BUF 1280*720*3
// 视频参数定义
#define PT_H264 96
#define PT_G726 97
#define PT_G711 8
#define PT_DATA 100
// global
static int g_iConnState = 0;
int ret = -1;
int outSize = 0;
const int nVideoLen = 1280 * 720;
const int nBufLen = 512000;
char *g_pVideoData = NULL;
char *g_pBufData = NULL;
int g_nCopyLen = 0;
int g_nBufLen = 0;
int g_nFullPackLen = 0;
int g_nNeedLen = 0;
unsigned int g_ts = 0;
int g_tsLen = 0;
char *m_srcInbuf = NULL;
//2. RTP数据包头格式：
typedef struct {
/* byte 0 */
unsigned short cc :4; /* CSRC count */
unsigned short x :1; /* header extension flag */
unsigned short p :1; /* padding flag */
unsigned short version :2; /* protocol version */
/* byte 1 */
unsigned short pt :7; /* payload type */ //pt说明： 96=>H.264, 97=>G.726, 8=>G.711a, 100=>报警数据
unsigned short marker :1; /* marker bit */
/* bytes 2, 3 */
unsigned short seqno :16; /* sequence number */
/* bytes 4-7 */
unsigned int ts; /* timestamp in ms */
/* bytes 8-11 */
unsigned int ssrc; /* synchronization source */
} RTP_HDR_S; // sizeof: 12
typedef struct {
unsigned char daollar; /*8, $:dollar sign(24 decimal)*/
unsigned char channelid; /*8, channel id*/
unsigned short resv; /*16, reseved*/
unsigned int payloadLen; /*32, payload length*/
RTP_HDR_S rtpHead; /*rtp head*/
} RTSP_ITLEAVED_HDR_S; // sizeof: 20
typedef struct {
unsigned char daollar; /*8, $:dollar sign(24 decimal)*/
unsigned char channelid; /*8, channel id*/
unsigned short resv; /*16, reseved*/
unsigned int payloadLen; /*32, payload length*/
} RTSP_H_S; // sizeof: 8
///////////////////////////////////////////////////////////////
// 处理接收视频，音频等数据
int RecvPackData(const char *pBuf, int len) {
const int N_RTP_HDR = sizeof(RTP_HDR_S);
if (len < N_RTP_HDR) {
printf("\n~~~~~~~~~~~~~~~~~~~~~ERR: PackData!");
return -1;
}
RTP_HDR_S rtpHead;
memcpy(&rtpHead, pBuf, N_RTP_HDR);
unsigned int ts = ntohl(rtpHead.ts);
//96=>H.264, 97=>G.726, 8=>G.711a, 100=>报警数据
if (rtpHead.pt == PT_H264) {
int nVideoLen = len - N_RTP_HDR;
if (ts != g_ts && g_ts > 0){
//[self showVideo:g_tsLen];
//满帧解码
__android_log_print(ANDROID_LOG_DEBUG, "jni_log","man yi zhen ,xia mian jie ma !");
int ret = DecodeH264(m_srcInbuf, g_tsLen);
if (ret < 1) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log","Decoding failure!** ret= %d", ret);
}
//清理
memset(m_srcInbuf,0,MAX_RGB_BUF);
g_tsLen = 0;
memcpy(&m_srcInbuf[g_tsLen], pBuf + N_RTP_HDR, nVideoLen); // 去除RTP_HDR头
g_tsLen += nVideoLen;
g_ts = ts;
} else {
memcpy(&m_srcInbuf[g_tsLen], pBuf + N_RTP_HDR, nVideoLen); // 去除RTP_HDR头
g_tsLen += nVideoLen;
g_ts = ts;
}
}
return 1;
}
// 解析通道
int ParseChannelData(const char *pBuf, int len)
{
const int N_H_S = sizeof(RTSP_H_S); // 8
const int N_HDR_LEN = sizeof(RTSP_ITLEAVED_HDR_S); // 20
memcpy(&g_pBufData[g_nBufLen], pBuf, len);
g_nBufLen += len;
if (g_nBufLen < N_HDR_LEN)
return 0;
if (g_nNeedLen == 0) {
RTSP_ITLEAVED_HDR_S header;
memset(&header, 0, N_HDR_LEN);
memcpy(&header, g_pBufData, N_HDR_LEN);
int packet_len = ntohl(header.payloadLen); // - sizeof(RTP_HDR_S);
unsigned int timestamp = ntohl(header.rtpHead.ts);
int streamType = header.rtpHead.pt;
printf("\npayloadLen: %d time: %d streamType: %d\n", packet_len,
timestamp, streamType);
if (packet_len > 0 && header.daollar == 0x24) //"$" // 验证
{
g_nFullPackLen = packet_len;
// 当前包不够一个nalu包
if (g_nBufLen < g_nFullPackLen + N_H_S) {
int nCopy = g_nBufLen - N_H_S;
memcpy(&g_pVideoData[0], &g_pBufData[N_H_S], nCopy);
g_nCopyLen = nCopy;
g_nBufLen = 0;
if (g_nFullPackLen - nCopy > 0) {
g_nNeedLen = g_nFullPackLen - nCopy;
}
} else // >= 单个nalu包
{
int nCopy = g_nFullPackLen;
memcpy(&g_pVideoData[0], &g_pBufData[N_H_S], nCopy);
g_nCopyLen = nCopy;
g_nNeedLen = 0;
//================================================
//FULL PACK
RecvPackData(g_pVideoData, nCopy);
int nRemain = g_nBufLen - (g_nFullPackLen + N_H_S);
g_nBufLen = 0;
if (nRemain > 0) {
char *pTemp = (char *) malloc(nRemain);
memcpy(pTemp, &g_pBufData[g_nFullPackLen + N_H_S], nRemain);
ParseChannelData(pTemp, nRemain);
free(pTemp);
}
}
return 0;
} else {
g_nCopyLen = 0;
g_nBufLen = 0;
g_nFullPackLen = 0;
g_nNeedLen = 0;
g_ts = 0;
return 0;
}
}
if (g_nNeedLen > 0) {
if (g_nNeedLen > MAX_RGB_BUF) {
g_nCopyLen = 0;
g_nBufLen = 0;
g_nFullPackLen = 0;
g_nNeedLen = 0;
return 0;
}
if (g_nBufLen < g_nNeedLen) {
int nCopy = g_nBufLen;
memcpy(&g_pVideoData[g_nCopyLen], g_pBufData, nCopy);
g_nCopyLen += nCopy;
g_nNeedLen -= nCopy;
g_nBufLen = 0;
} else {
int nCopy = g_nNeedLen;
memcpy(&g_pVideoData[g_nCopyLen], g_pBufData, nCopy);
g_nCopyLen += nCopy;
g_nNeedLen = 0;
//================================================
//FULL PACK
RecvPackData(g_pVideoData, g_nFullPackLen);
int nRemain = g_nBufLen - nCopy;
g_nBufLen = 0;
if (nRemain > 0) {
char *pTemp = (char *) malloc(nRemain);
memcpy(pTemp, &g_pBufData[nCopy], nRemain);
ParseChannelData(pTemp, nRemain);
free(pTemp);
}
}
}
}
//====================================================
JNIEXPORT jint JNICALL Java_HttpCamera_HttpJniNative_init(JNIEnv* env,
jobject thiz) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "Start: init decode");
m_width = -1;
m_height = -1;
if (g_bInit == 1){
return -1;
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "Err: init");
}
if (g_pVideoData == NULL) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 111");
g_pVideoData = (char *) malloc(nVideoLen);
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 222");
g_pBufData = (char *) malloc(nBufLen);
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 333");
m_srcInbuf = (char *) malloc(MAX_RGB_BUF);
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 444");
}
//avcodec_init();
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 555");
av_register_all(); // Register all formats and codecs
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 666");
m_pCodec = avcodec_find_decoder(CODEC_ID_H264);
if (!m_pCodec) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log",
"Err: avcodec_find_decoder : CODEC_ID_H264 = %d",
(int) CODEC_ID_H264);
return -1;
}
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 777");
m_pCodecCtx = avcodec_alloc_context3(m_pCodec);
if (!m_pCodecCtx) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log",
"Err: avcodec_alloc_context3");
return -2;
}
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 888");
if (avcodec_open2(m_pCodecCtx, m_pCodec,NULL) < 0)
return -3;
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 999");
m_pFrame = avcodec_alloc_frame();
if (!m_pFrame) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log",
"Err: avcodec_alloc_frame");
return -4;
}
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "malloc 101010");
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "finish: init decode");
av_init_packet(&m_packet);
g_bInit = 1;
g_iFrame = 0;
return 1;
}
/*
* Class: h264_com_VView
* Method: UninitDecoder
* Signature: ()I
*/
JNIEXPORT jint JNICALL Java_HttpCamera_HttpJniNative_finit(JNIEnv* env,
jobject thiz) {
if (g_bInit <= 0)
return -1;
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "End: close decode");
if (g_pVideoData == NULL) {
free(g_pVideoData);
free(g_pBufData);
free(m_srcInbuf);
g_pVideoData = NULL;
g_pBufData = NULL;
m_srcInbuf = NULL;
}
// Close the codec
if (m_pCodecCtx) {
avcodec_close(m_pCodecCtx);
m_pCodecCtx = NULL;
}
// Free the YUV frame
if (m_pFrame != NULL) {
av_free(m_pFrame);
m_pFrame = NULL;
}
if(bPicture)
FreePicture();
m_width = -1;
m_height = -1;
g_bInit = 0;
return 1;
}
/*
* Class: h264_com_VView
* Method: DecoderNal
* Signature: ([B[I)I
*/
int InitPicture()
{
frame_rgb = avcodec_alloc_frame();
if(!frame_rgb)
{
__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "End:Init Picture");
return -1;
}
int numBytes = avpicture_get_size(PIX_FMT_RGB565,m_width,m_height);
fill_buffer = (char *)av_malloc(numBytes * sizeof(char));
avpicture_fill((AVPicture *)frame_rgb, fill_buffer, PIX_FMT_RGB565,m_width,m_height);
img_convert_ctx = sws_getContext(m_width,m_height,m_pCodecCtx->pix_fmt,
m_width, m_height, PIX_FMT_RGB565, SWS_BICUBIC, NULL, NULL, NULL);
bPicture = JNI_TRUE;
return 1;
}
int FreePicture()
{
if(fill_buffer!=NULL)
{
av_free(fill_buffer);
fill_buffer = NULL;
}
if(frame_rgb!=NULL){
av_free(frame_rgb);
frame_rgb = NULL;
}
sws_freeContext(img_convert_ctx);
bPicture = JNI_FALSE;
return 1;
}
int DecodeH264(char *pByte, int nalLen) {
if (g_bInit <= 0) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log",
"Err: No init decode");
return -1;
}
int got_picture;
int numBytes;
// jbyte *pByte = (jbyte*)(*env)->GetByteArrayElements(env, in, 0);
int nSrcLen = nalLen;
m_packet.size = nSrcLen;
m_packet.data = (unsigned char *) pByte;
int consumed_bytes = avcodec_decode_video2(m_pCodecCtx, m_pFrame,
&got_picture, &m_packet);
if (consumed_bytes > 0) {
if (m_pFrame->data[0]) {
m_width = m_pCodecCtx->width;
m_height = m_pCodecCtx->height;
__android_log_print(ANDROID_LOG_DEBUG, "jni_log"," w:%d---- h:%d",m_width,m_height);
if(!bPicture)
InitPicture();
}
}else
{
m_width = -1;
m_height = -1;
}
// (*env)->ReleaseByteArrayElements(env, in, pByte, 0);
return 2;
}
JNIEXPORT jint JNICALL Java_HttpCamera_HttpJniNative_PackData(JNIEnv* env, jobject thiz, jbyteArray in, jint nalLen)
{
jbyte * Buf = (jbyte*)(*env)->GetByteArrayElements(env, in, 0);
//__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "enter into ");
//__android_log_print(ANDROID_LOG_DEBUG, "jni_log", "nalLen = %d",nalLen);
ParseChannelData(Buf,nalLen);
(*env)->ReleaseByteArrayElements(env, in, Buf, 0);
}
JNIEXPORT jint JNICALL Java_HttpCamera_HttpJniNative_OutFrameData(JNIEnv* env,
jobject thiz, jbyteArray out) {
jbyte *pByte = (jbyte*) (*env)->GetByteArrayElements(env, out, 0);
if (g_bInit <= 0) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log",
"Err: OutFrameData, No init decode");
return -1;
}
if (m_width <= 0 || m_height <= 0) {
__android_log_print(ANDROID_LOG_DEBUG, "jni_log",
"Err: jni::decode() w <0 or h < 0");
}
__android_log_print(ANDROID_LOG_DEBUG, "jni_log",
"### OutFrame: %d w:%d h:%d", g_iFrame++, m_width, m_height);
int ret = sws_scale(img_convert_ctx, m_pFrame->data,m_pFrame->linesize, 0,m_height,frame_rgb->data, frame_rgb->linesize);
memcpy(pByte,frame_rgb->data[0],m_height * m_width * 2);
if (pByte != NULL) {
(*env)->ReleaseByteArrayElements(env, out, pByte, 0);
}
return 1;
}
JNIEXPORT jint JNICALL Java_HttpCamera_HttpJniNative_GetWidth(JNIEnv* env,
jobject thiz) {
if (m_width > 0)
return m_width;
return -1;
}
JNIEXPORT jint JNICALL Java_HttpCamera_HttpJniNative_GetHeight(JNIEnv* env,
jobject thiz) {
if (m_height > 0)
return m_height;
return -1;
}