重编译 microsip 和 pjsip 支持 mp3 录音

前言

使用 MicroSip 源码编译后，在录音配置界面虽然有 mp3 格式选项，但是实际录音后不会生成mp3 文件夹，而选择wav格式却可以正常生成 wav 文件。

经测试发现需要重新编译 pjsip 工程，加入 mp3 编码才可以。

操作步骤大概如下：

1.pjmedia 项目加入如下 pjsip2.12.1版本 third_party/mp3 文件夹中的3个文件

2.在pjmedia.h 文件中包含刚引入的 mp3_port.h

//...
#include 
#include 
#include 
//增加mp3编码 [2022-7-28 By Pafey]
#include "../../third_party/mp3/mp3_port.h"
//...
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3.修改 pjsua_lib 项目的 pjsua_aud.c 文件中的 pjsua_recorder_create 函数

在录音格式判断那里，源码只有处理wav格式，需要多加个mp3格式进去。

需要注意的是第七个参数 pjmedia_mp3_encoder_option param_option;

主要是跟mp3文件的质量有关：

vbr：指定是否应使用可变比特率。可变比特率通常会产生更好的质量，但代价可能是文件更大。

bit_rate：目标比特率，单位为bps。如果启用了VBR，此设置指定请求的平均比特率，并将使编码器忽略质量设置。对于CBR，这指定了实际的比特率，如果该选项为零，它将被设置为采样率乘以通道数量。

quality：编码质量，0-9，以0为最高质量。对于VBR，质量设置只在bit_rate设置为零时生效。

关键代码如下：

    if (file_format == FMT_WAV) {
	status = pjmedia_wav_writer_port_create(pool, path,
						pjsua_var.media_cfg.clock_rate,
						pjsua_var.mconf_cfg.channel_count,
						pjsua_var.mconf_cfg.samples_per_frame,
						pjsua_var.mconf_cfg.bits_per_sample,
						options, 0, &port);
    }
     else if (file_format == FMT_MP3)
    {
    	//增加mp3编码 [2022-7-28 By Pafey]
		pjmedia_mp3_encoder_option param_option;
		param_option.vbr = PJ_TRUE;
		param_option.bit_rate = 0;
		param_option.quality = 6;//0-9,0质量最高，vbr启用时，仅bit_rate为0时有效
		
		status = pjmedia_mp3_writer_port_create(pool, path,
			pjsua_var.media_cfg.clock_rate,
			pjsua_var.mconf_cfg.channel_count,
			pjsua_var.mconf_cfg.samples_per_frame,
			pjsua_var.mconf_cfg.bits_per_sample,
			&param_option, &port);

    } else {
	PJ_UNUSED_ARG(enc_param);
	port = NULL;
	status = PJ_ENOTSUP;
    }
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pjsua_recorder_create 函数完整代码：

/*
 * Create a file recorder, and automatically connect this recorder to
 * the conference bridge.
 */
PJ_DEF(pj_status_t) pjsua_recorder_create( const pj_str_t *filename,
					   unsigned enc_type,
					   void *enc_param,
					   pj_ssize_t max_size,
					   unsigned options,
					   pjsua_recorder_id *p_id)
{
    enum Format
    {
	FMT_UNKNOWN,
	FMT_WAV,
	FMT_MP3,
    };
    unsigned slot, file_id;
    char path[PJ_MAXPATH];
    pj_str_t ext;
    int file_format;
    pj_pool_t *pool = NULL;
    pjmedia_port *port;
    pj_status_t status = PJ_SUCCESS;

    /* Filename must present */
    PJ_ASSERT_RETURN(filename != NULL, PJ_EINVAL);

    /* Don't support max_size at present */
    PJ_ASSERT_RETURN(max_size == 0 || max_size == -1, PJ_EINVAL);

    /* Don't support encoding type at present */
    PJ_ASSERT_RETURN(enc_type == 0, PJ_EINVAL);

    if (filename->slen >= PJ_MAXPATH)
    	return PJ_ENAMETOOLONG;
    if (filename->slen < 4)
    	return PJ_EINVALIDOP;

    PJ_LOG(4,(THIS_FILE, "Creating recorder %.*s..",
	      (int)filename->slen, filename->ptr));
    pj_log_push_indent();

    if (pjsua_var.rec_cnt >= PJ_ARRAY_SIZE(pjsua_var.recorder)) {
	pj_log_pop_indent();
	return PJ_ETOOMANY;
    }

    /* Determine the file format */
    ext.ptr = filename->ptr + filename->slen - 4;
    ext.slen = 4;

    if (pj_stricmp2(&ext, ".wav") == 0)
	file_format = FMT_WAV;
    else if (pj_stricmp2(&ext, ".mp3") == 0)
	file_format = FMT_MP3;
    else {
	PJ_LOG(1,(THIS_FILE, "pjsua_recorder_create() error: unable to "
			     "determine file format for %.*s",
			     (int)filename->slen, filename->ptr));
	pj_log_pop_indent();
	return PJ_ENOTSUP;
    }

    PJSUA_LOCK();

    for (file_id=0; file_id<PJ_ARRAY_SIZE(pjsua_var.recorder); ++file_id) {
	if (pjsua_var.recorder[file_id].port == NULL)
	    break;
    }

    if (file_id == PJ_ARRAY_SIZE(pjsua_var.recorder)) {
	/* This is unexpected */
	pj_assert(0);
	status = PJ_EBUG;
	goto on_return;
    }

    pj_memcpy(path, filename->ptr, filename->slen);
    path[filename->slen] = '\0';

    pool = pjsua_pool_create(get_basename(path, (unsigned)filename->slen), 1000, 
			     1000);
    if (!pool) {
	status = PJ_ENOMEM;
	goto on_return;
    }

    if (file_format == FMT_WAV) {
	status = pjmedia_wav_writer_port_create(pool, path,
						pjsua_var.media_cfg.clock_rate,
						pjsua_var.mconf_cfg.channel_count,
						pjsua_var.mconf_cfg.samples_per_frame,
						pjsua_var.mconf_cfg.bits_per_sample,
						options, 0, &port);
    }else if (file_format == FMT_MP3)
    {
		pjmedia_mp3_encoder_option param_option;
		param_option.vbr = PJ_TRUE;
		param_option.bit_rate = 0;
		param_option.quality = 6;//0-9,0质量最高，vbr启用时，仅bit_rate为0时有效
		//增加mp3编码 [2022-7-28 By Pafey]
		status = pjmedia_mp3_writer_port_create(pool, path,
			pjsua_var.media_cfg.clock_rate,
			pjsua_var.mconf_cfg.channel_count,
			pjsua_var.mconf_cfg.samples_per_frame,
			pjsua_var.mconf_cfg.bits_per_sample,
			&param_option, &port);

    } else {
	PJ_UNUSED_ARG(enc_param);
	port = NULL;
	status = PJ_ENOTSUP;
    }

    if (status != PJ_SUCCESS) {
	pjsua_perror(THIS_FILE, "Unable to open file for recording", status);
	goto on_return;
    }

    status = pjmedia_conf_add_port(pjsua_var.mconf, pool,
				   port, filename, &slot);
    if (status != PJ_SUCCESS) {
	pjmedia_port_destroy(port);
	goto on_return;
    }

    pjsua_var.recorder[file_id].port = port;
    pjsua_var.recorder[file_id].slot = slot;
    pjsua_var.recorder[file_id].pool = pool;

    if (p_id) *p_id = file_id;

    ++pjsua_var.rec_cnt;

    PJSUA_UNLOCK();

    PJ_LOG(4,(THIS_FILE, "Recorder created, id=%d, slot=%d", file_id, slot));

    pj_log_pop_indent();
    return PJ_SUCCESS;

on_return:
    PJSUA_UNLOCK();
    if (pool) pj_pool_release(pool);
    pj_log_pop_indent();
    return status;
}
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4.编译 libpjproject 项目

生成 libpjproject-i386-Win32-vc14-Release.lib 库文件。就可以被sip软电话引入使用了。我这里用的是MicroSip，在配置界面录音选择 mp3

打个电话就可以生成mp3文件了，搞了一天终于完美收工。

问题记录

pjsip编译完成后，引入库文件依然不能生成mp3文件，后面调试进

pjmedia_mp3_writer_port_create -> init_blade_dll 
1

这个初始化需要加载 LAME_ENC.DLL
去 microsip 安装文件夹内拷一个出来放到自己编译的microsip exe所在路径就成功了
文末放了下载地址

#include 
#define DLL_NAME    PJ_T("LAME_ENC.DLL")

/*
 * Load BladeEncoder DLL.
 */
static pj_status_t init_blade_dll(void)
{
    if (BladeDLL.refCount == 0) {
	#define GET_PROC(type, name)  \
	    BladeDLL.name = (type)GetProcAddress(BladeDLL.hModule, PJ_T(#name)); \
	    if (BladeDLL.name == NULL) { \
		PJ_LOG(1,(THIS_FILE, "Unable to find %s in %s", #name, DLL_NAME)); \
		return PJ_RETURN_OS_ERROR(GetLastError()); \
	    }

	BE_VERSION beVersion;
	BladeDLL.hModule = (void*)LoadLibrary(DLL_NAME);
	if (BladeDLL.hModule == NULL) {
	    pj_status_t status = PJ_RETURN_OS_ERROR(GetLastError());
	    char errmsg[PJ_ERR_MSG_SIZE];

	    pj_strerror(status, errmsg, sizeof(errmsg));
	    PJ_LOG(1,(THIS_FILE, "Unable to load %s: %s", DLL_NAME, errmsg));
	    return status;
	}
//...
	}
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编译的库文件

库文件和编码dll下载地址