x265源码分析：main函数及CLIOptions结构体解释

/**
* 返回码信息：
* 0 – 编码成功；
* 1 – 命令行解释失败；
* 2 – 编码器打开失败；
* 3 – 生成流头部失败；
* 4 – 编码出错；
* 5 – 打开csv文件失败.
*/
int main(int argc, char **argv)
{
// 获取控制台窗口的标题,保存在静态数组orgConsoleTitle中
GetConsoleTitle(orgConsoleTitle, CONSOLE_TITLE_SIZE);

// 取消电源管理，避免睡眠、待机
SetThreadExecutionState(ES_CONTINUOUS|ES_SYSTEM_REQUIRED|ES_AWAYMODE_REQUIRED);

ReconPlay* reconPlay = NULL;
CLIOptions cliopt;

// 分析命令行参数，对编码器的参数进行设置，打开相关文件
if (cliopt.parse(argc, argv))
{
cliopt.destroy();
if (cliopt.api)
cliopt.api->param_free(cliopt.param);
exit(1);
}

x265_param*   param = cliopt.param;
const x265_api* api = cliopt.api;

/* This allows muxers to modify bitstream format */
cliopt.output->setParam(param);

if (cliopt.reconPlayCmd)
reconPlay = new ReconPlay(cliopt.reconPlayCmd, *param);

// 命令行解释阶段，依据参数profile的值可选择不同的 libx265 API.
// 打开编码器
x265_encoder *encoder = api->encoder_open(param);
if (!encoder)
{
x265_log(param, X265_LOG_ERROR, "failed to open encoder\n");
cliopt.destroy();
api->param_free(param);
api->cleanup();
exit(2);
}

// 获取编码参数
api->encoder_parameters(encoder, param);

if (cliopt.csvfn)
{
cliopt.csvfpt = x265_csvlog_open(*api, *param, cliopt.csvfn, cliopt.csvLogLevel);
if (!cliopt.csvfpt)
{
x265_log_file(param, X265_LOG_ERROR, "Unable to open CSV log file <%s>,
aborting\n", cliopt.csvfn);
cliopt.destroy();
if (cliopt.api)
cliopt.api->param_free(cliopt.param);
exit(5);
}
}

// 当按下Ctrl-C的时候，当前执行程序调用指针函数sigint_handler 执行完后，再返回原
// 来执行的地方接着往下走。 此处将变量b_ctrl_c设置为1，停止当前编码工作。
if (signal(SIGINT, sigint_handler) == SIG_ERR)
x265_log(param, X265_LOG_ERROR, "Unable to register CTRL+C handler: %s\n", strerror(errno));

// 定义x265的输入pic_orig和输出pic_out
x265_picture pic_orig, pic_out;
x265_picture *pic_in = &pic_orig;       // 获取x265的输入pic_orig的地址

// Allocate recon picture if analysisMode is enabled
std::priority_queue<int64_t>* pts_queue = cliopt.output->needPTS() ? new
std::priority_queue<int64_t>() : NULL;
x265_picture *pic_recon = (cliopt.recon || !!param->analysisMode || pts_queue
|| reconPlay || cliopt.csvLogLevel) ? &pic_out : NULL;

// 输入、输出的帧数
uint32_t inFrameCount  = 0;
uint32_t outFrameCount = 0;

x265_nal *p_nal;
x265_stats stats;
uint32_t nal;
int16_t *errorBuf = NULL;
int ret = 0;

// 如果不需要复制sps和pps放在每个关键帧的前面，则直接编码视频流的头
if (!param->bRepeatHeaders)
{
if (api->encoder_headers(encoder, &p_nal, &nal) < 0)
{
x265_log(param, X265_LOG_ERROR, "Failure generating stream headers\n");
ret = 3;
goto fail;
}
else
// 更新总字节数：增加头部字节数目
cliopt.totalbytes += cliopt.output->writeHeaders(p_nal, nal);
}

api->picture_init(param, pic_in);

if (cliopt.bDither)
{
errorBuf = X265_MALLOC(int16_t, param->sourceWidth + 1);
if (errorBuf)
memset(errorBuf, 0, (param->sourceWidth + 1) * sizeof(int16_t));
else
cliopt.bDither = false;
}

// main encoder loop（编码主循环）
while (pic_in && !b_ctrl_c)
{
pic_orig.poc = inFrameCount;
if (cliopt.qpfile)
{
if (!cliopt.parseQPFile(pic_orig))
{
x265_log(NULL, X265_LOG_ERROR, "can't parse qpfile for frame %d\n",
pic_in->poc);
fclose(cliopt.qpfile);
cliopt.qpfile = NULL;
}
}

// 待编码的帧数大于0 且 输入的帧数大于或等于将要编码的帧数
if (cliopt.framesToBeEncoded && inFrameCount >= cliopt.framesToBeEncoded)
pic_in = NULL;
// 成功读取一帧，则输入帧数增加1
else if (cliopt.input->readPicture(pic_orig))
inFrameCount++;
else
pic_in = NULL;

if (pic_in)
{
if (pic_in->bitDepth > param->internalBitDepth && cliopt.bDither)
{
x265_dither_image(*api, *pic_in, cliopt.input->getWidth(), cliopt.input->getHeight(), errorBuf, param->internalBitDepth);
pic_in->bitDepth = param->internalBitDepth;
}
/* Overwrite PTS */
pic_in->pts = pic_in->poc;
}

// 进行编码入口函数，读入几十帧（具体多少帧依赖命令行参数的设置）之后才开始编码。
// numEncoded是本次编码出来的帧数，大部分情况下为1，如果是负数表示编码出错。
int numEncoded = api->encoder_encode(encoder, &p_nal, &nal, pic_in, pic_recon);
if (numEncoded < 0)
{
b_ctrl_c = 1;
ret = 4;
break;
}

if (reconPlay && numEncoded)
reconPlay->writePicture(*pic_recon);

if (numEncoded && pic_recon && cliopt.recon)
cliopt.recon->writePicture(pic_out);

if (nal)
{
cliopt.totalbytes += cliopt.output->writeFrame(p_nal, nal, pic_out);
if (pts_queue)
{
pts_queue->push(-pic_out.pts);
if (pts_queue->size() > 2)
pts_queue->pop();
}
}

// 打印编码帧的具体信息
cliopt.printStatus(outFrameCount);
if (numEncoded && cliopt.csvLogLevel)
x265_csvlog_frame(cliopt.csvfpt, *param, *pic_recon, cliopt.csvLogLevel);
} // 编码主循环结束

/* Flush the encoder */
// 前面读入几十帧之后才开始编码，此处其实就是处理对应的倒数的几十帧，将其存储
while (!b_ctrl_c)
{
... ...
}

/* clear progress report */
if (cliopt.bProgress)
fprintf(stderr, "%*s\r", 80, " ");
fail:
... ...
return ret;
}

/* 命令行接口 */
struct CLIOptions
{
InputFile*  input;          // 输入文件，抽象类, 定义在 \input\input.h 中
ReconFile*  recon;          // 重构文件，抽象类，定义在 \output\output.h 中
OutputFile* output;         // 输出文件，抽象类，定义在 \output\output.h 中
FILE*       qpfile;         // 量化因子文件指针
FILE*       csvfpt;         // csv日志文件指针
const char* csvfn;          // csv日志文件名
const char* reconPlayCmd;
const x265_api* api;        //
x265_param* param;          // x265编码器参数集
bool bProgress;             // 是否输出编码进度和其他一些编码状态数据
bool bForceY4m;             // 如果输入文件是Y4M格式，需要强制指定输入格式
bool bDither;
int csvLogLevel;            // csv日志级别，log level定义在 x265.h中
uint32_t seek;              // 输入视频起始需要跳过的帧数
uint32_t framesToBeEncoded; // 待编码的帧数
uint64_t totalbytes;        // 已编码的数据字节数
int64_t startTime;          // 起始编码时间点
int64_t prevUpdateTime;     // 上一次编码信息输出的时间点

/* in microseconds，相邻两次编码状态输出的最小时间间隔，单位微妙 */
static const int UPDATE_INTERVAL = 250000;

// 构造函数，初始化上述各成员变量
CLIOptions()
{
… … … …
}

void destroy();
void printStatus(uint32_t frameNum);        // 打印编码状态信息
bool parse(int argc, char **argv);          // 解释命令行参数
bool parseQPFile(x265_picture &pic_org);    // 解释量化因子QP文件
};

/* 打印编码状态信息 */
void CLIOptions::printStatus(uint32_t frameNum)
{
char buf[200];
int64_t time = x265_mdate();

// 是否输出编码状态信息取决于：进度开关、当前编码帧数、上次信息输出和当前时间的间隔
if (!bProgress || !frameNum || (prevUpdateTime && time - prevUpdateTime < UPDATE_INTERVAL))
return;

// 计算编码帧率和码率
int64_t elapsed = time - startTime;
double fps = elapsed > 0 ? frameNum * 1000000. / elapsed : 0;
float bitrate = 0.008f * totalbytes * (param->fpsNum / param->fpsDenom) / ((float)frameNum);
if (framesToBeEncoded)
{
int eta = (int)(elapsed * (framesToBeEncoded - frameNum) / ((int64_t)frameNum * 1000000));
sprintf(buf, "x265 [%.1f%%] %d/%d frames, %.2f fps, %.2f kb/s,
eta %d:%02d:%02d", 100. * frameNum / framesToBeEncoded, frameNum,
framesToBeEncoded, fps, bitrate, eta / 3600, (eta / 60) % 60, eta % 60);
}
else
sprintf(buf, "x265 %d frames: %.2f fps, %.2f kb/s", frameNum, fps, bitrate);

fprintf(stderr, "%s  \r", buf + 5);
SetConsoleTitle(buf);
fflush(stderr);             // needed in windows
prevUpdateTime = time;
}

/* 解释命令行参数 */
bool CLIOptions::parse(int argc, char **argv)
{
bool bError = false;
int  bShowHelp = false;
int  inputBitDepth = 8;
int  outputBitDepth = 0;
int  reconFileBitDepth = 0;
const char *inputfn = NULL;         // 输入文件名
const char *reconfn = NULL;         // 重构文件名
const char *outputfn = NULL;        // 输出文件名
const char *preset = NULL;
const char *tune = NULL;
const char *profile = NULL;

if (argc <= 1)
{
x265_log(NULL, X265_LOG_ERROR, "No input file. Run x265 --help for a list of options.\n");
return true;
}

/* Presets are applied before all other options. */
for (optind = 0;; )
{
int c = getopt_long(argc, argv, short_options, long_options, NULL);
if (c == -1)              // 选项结束或错误，退出循环
break;
else if (c == 'p')
preset = optarg;
else if (c == 't')
tune = optarg;
else if (c == 'D')
outputBitDepth = atoi(optarg);
else if (c == 'P')
profile = optarg;
else if (c == '?')
bShowHelp = true;
}

if (!outputBitDepth && profile)
{
/* try to derive the output bit depth from the requested profile */
if (strstr(profile, "10"))
outputBitDepth = 10;
else if (strstr(profile, "12"))
outputBitDepth = 12;
else
outputBitDepth = 8;
}

api = x265_api_get(outputBitDepth);
if (!api)
{
x265_log(NULL, X265_LOG_WARNING, "falling back to default bit-depth\n");
api = x265_api_get(0);
}

param = api->param_alloc();
if (!param)
{
x265_log(NULL, X265_LOG_ERROR, "param alloc failed\n");
return true;
}

if (api->param_default_preset(param, preset, tune) < 0)
{
x265_log(NULL, X265_LOG_ERROR, "preset or tune unrecognized\n");
return true;
}

if (bShowHelp)
{
printVersion(param, api);
showHelp(param);
}

for (optind = 0;; )
{
int long_options_index = -1;
int c = getopt_long(argc, argv, short_options, long_options, &long_options_index);
if (c == -1)
break;

switch (c)
{
case 'h':
printVersion(param, api);
showHelp(param);
break;

case 'V':
printVersion(param, api);
x265_report_simd(param);
exit(0);
default:
if (long_options_index < 0 && c > 0)
{
for (size_t i = 0; i < sizeof(long_options) / sizeof(long_options[0]); i++)
{
if (long_options[i].val == c)
{
long_options_index = (int)i;
break;
}
}

if (long_options_index < 0)
{
/* getopt_long might have already printed an error message */
if (c != 63)
x265_log(NULL, X265_LOG_WARNING, "internal error: short option '%c' has no long option\n", c);
return true;
}
}
... ...
}
... ...
}