V2.0.3

1.没有老师，但是有两个学生时，默认使用一对多布局
2.一对一时，老师和学生的视频尺寸不同时，合成的视频高度取老师视频高度加上学生视频高度（之前版本假定老师和学生视频大小一致，使用的是最大高度的二倍）
3.一对多时，支持学生的视频尺寸不一致的情况（之前版本假定只有一种视频尺寸，其它尺寸视为异常）
4.一对多时，最多只在老师视频下部排4个学生，多于4个学生的情况，扩大合成视频的高度，把学生视频排列在老师视频下方，保证老师视频部分最多只有一排学生视频，避免老师视频被过度遮挡

 #include "AVDecoder.h"
-
+extern "C" {
+#include <libswscale/swscale.h> 
+}
 
 CAVDecoder::CAVDecoder() :
 _a_start_time_ms(INT64_MAX),
@@ -9,7 +11,12 @@ _cur_v_ts_ms(INT64_MAX),
 _end_time_ms(0),
 _cur_a_frame(NULL),
 _cur_v_frame(NULL),
-_media_role(mr_student)
+_media_role(mr_student),
+_scaled_width(0),
+_scaled_height(0),
+_src_width(0),
+_src_height(0),
+_sws_ctx(NULL)
 {
 }
 
@@ -18,6 +25,10 @@ CAVDecoder::~CAVDecoder()
 {
 	free_cur_v_frame();
 	free_cur_a_frame();
+	if (_sws_ctx) {
+		sws_freeContext(_sws_ctx);
+		_sws_ctx = NULL;
+	}
 }
 
 int CAVDecoder::add(media_info &info)
@@ -116,6 +127,32 @@ void CAVDecoder::free_cur_a_frame()
 	}
 }
 
+int CAVDecoder::scale_frame(AVFrame * pFrame, AVFrame * pScaledFrame, int scaled_width, int scaled_height)
+{
+	if (pFrame->width == _src_width && pFrame->height == _src_height && scaled_width == _scaled_width && scaled_height == _scaled_height) {
+		return sws_scale(_sws_ctx, pFrame->data, pFrame->linesize, 0, pFrame->height,
+			pScaledFrame->data, pScaledFrame->linesize);
+	}
+	else {
+		if (_sws_ctx) {
+			sws_freeContext(_sws_ctx);
+			_sws_ctx = NULL;
+		}
+		_sws_ctx = sws_getContext(pFrame->width, pFrame->height, AV_PIX_FMT_YUV420P,
+			scaled_width, scaled_height, AV_PIX_FMT_YUV420P, SWS_BILINEAR,
+			NULL, NULL, NULL);
+		if (!_sws_ctx) {
+			return -1;
+		}
+		_src_width = pFrame->width;
+		_src_height = pFrame->height;
+		_scaled_width = scaled_width;
+		_scaled_height = scaled_height;
+		return sws_scale(_sws_ctx, pFrame->data, pFrame->linesize, 0, pFrame->height,
+			pScaledFrame->data, pScaledFrame->linesize);
+	}
+}
+
 void CAVDecoder::free_cur_v_frame()
 {
 	if (_cur_v_frame) {

@@ -37,5 +37,15 @@ protected:
 protected:
 	void free_cur_v_frame();
 	void free_cur_a_frame();
+public:
+	int scale_frame(AVFrame * pFrame, AVFrame * pScaledFrame, int scaled_width, int scaled_height);
+
+protected:
+	int _scaled_width;
+	int _scaled_height;
+	int _src_width;
+	int _src_height;
+	struct SwsContext * _sws_ctx;
+
 };
 

@@ -13,8 +13,13 @@ extern "C" {
 uint8_t blank_r = 0x16;
 uint8_t blank_g = 0x5a;
 uint8_t blank_b = 0x82;
+int pip_x_gap = 8;
+int pip_y_gap = 4;
+int pip_x_reduce = 3;
+int pip_y_reduce = 3;
+int pip_x_border = 4;
 
-CAVTranscoder::CAVTranscoder(bool bOne2One, int width_teacher, int height_teacher, int width_student, int height_student) :
+CAVTranscoder::CAVTranscoder(bool bOne2One, int width_teacher, int height_teacher, int width_student, int height_student, bool has_teacher, int max_audio) :
 _start_time(INT64_MAX),
 _all_processed(true),
 _nOutputWidth(320),
@@ -29,7 +34,9 @@ _scaled_frame_h_w(NULL),
 _scaled_frame_h_h(NULL),
 _last_videos_got(-1),
 _teacherFrame(NULL),
-_studentFrame(NULL)
+_studentFrame(NULL),
+_pip_width(0),
+_pip_height(0)
 {
 	_teacher_width = width_teacher;
 	_teacher_height = height_teacher;
@@ -38,6 +45,7 @@ _studentFrame(NULL)
 
 	_scaled_width = _teacher_width * 10 / 32;
 	_scaled_height = _teacher_height * 10 / 32;
+
 	_one2one = bOne2One;
 	if (_one2one) {
 		_nOutputWidth = max(_teacher_width, _student_width);
@@ -45,7 +53,23 @@ _studentFrame(NULL)
 	}
 	else {
 		_nOutputWidth = _teacher_width;
-		_nOutputHeight = _teacher_height;
+		int n_students = (max_audio - (has_teacher ? 1 : 0));
+		int extent_student_lines = n_students  / 4;
+		int part_student = n_students % 4;
+
+		_pip_width = _scaled_height - pip_x_reduce;  //use the scaled height,not the scaled width as pip_width
+		_pip_height = _scaled_height - pip_y_reduce;
+		
+		_nOutputHeight = _teacher_height + extent_student_lines * (_pip_height + pip_y_gap) - (part_student == 0 ? (pip_y_gap) : 0);
+		_nOutputHeight = ((_nOutputHeight + 1) / 2) * 2;
+
+		int student_line_width = 4 * (_pip_width)+3 * pip_x_gap + 2 * pip_x_border;
+		if (student_line_width > _nOutputWidth) {
+			pip_x_gap -= (student_line_width - _nOutputWidth) / 3;
+		}
+		student_line_width = 4 * (_pip_width) + 3 * pip_x_gap + 2 * pip_x_border;
+		pip_x_border -= (student_line_width - _nOutputWidth) / 2;
+
 
 		init_scale_context(&_sws_ctx_w_h, &_scaled_frame_w_h, _student_width, _student_height, _scaled_width, _scaled_height);
 		init_scale_context(&_sws_ctx_h_w, &_scaled_frame_h_w, _student_height, _student_width, _scaled_height, _scaled_width);
@@ -356,12 +380,17 @@ int CAVTranscoder::open_output_file(const char *filename)
 		}
 		if (_teacherFrame) {
 			fillDestFrame(pDstFrame, _teacherFrame, 0, 0);
+			if (_nOutputHeight > _teacherFrame->height) {
+				memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, pDstFrame->linesize[0] * (_nOutputHeight - _teacherFrame->height));
+				memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, pDstFrame->linesize[1] * (_nOutputHeight - _teacherFrame->height) / 2);
+				memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, pDstFrame->linesize[2] * (_nOutputHeight - _teacherFrame->height) / 2);
+			}
 		}
 		else
 		{//fill with pure color
-			memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _nOutputHeight);
-			memset(pDstFrame->data[1], _blank_u, _nOutputWidth *_nOutputHeight / 4);
-			memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _nOutputHeight / 4);
+			memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _nOutputHeight);
+			memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _nOutputHeight / 2);
+			memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _nOutputHeight / 2);
 		}
 
 		int imageIdx = 0;
@@ -382,7 +411,7 @@ int CAVTranscoder::open_output_file(const char *filename)
 						continue;
 					}
 					_scaled_frame_w_h->pkt_dts = pFrame->pkt_dts;//pass rotation
-					fillDestFrame(pDstFrame, _scaled_frame_w_h, _teacher_width - (imageIdx % 4 + 1) * (_scaled_height + 5) + 4, _teacher_height - _scaled_height + 3 - (_scaled_height + 1)*(imageIdx / 4), (_scaled_width - _scaled_height) / 2, 0, _scaled_height - 3, _scaled_height - 3);
+					fillDestFrame(pDstFrame, _scaled_frame_w_h, _teacher_width - (imageIdx % 4 + 1) * (_pip_width + pip_x_gap) - pip_x_border + pip_x_gap, _nOutputHeight - _scaled_height + pip_y_reduce - (_pip_height + pip_y_gap)*(imageIdx / 4), (_scaled_width - _scaled_height) / 2, 0, _pip_width, _pip_height);
 				}
 				else if (pFrame->width == _student_height && pFrame->height == _student_width) {
 					h = sws_scale(_sws_ctx_h_w, pFrame->data, pFrame->linesize, 0, pFrame->height,
@@ -392,7 +421,7 @@ int CAVTranscoder::open_output_file(const char *filename)
 						continue;
 					}
 					_scaled_frame_h_w->pkt_dts = pFrame->pkt_dts;//pass rotation
-					fillDestFrame(pDstFrame, _scaled_frame_h_w, _teacher_width - (imageIdx % 4 + 1) * (_scaled_height + 5) + 4, _teacher_height - _scaled_height + 3 - (_scaled_height + 1)*(imageIdx / 4), 0, (_scaled_width - _scaled_height) / 2, _scaled_height - 3, _scaled_height - 3);
+					fillDestFrame(pDstFrame, _scaled_frame_h_w, _teacher_width - (imageIdx % 4 + 1) * (_pip_width + pip_x_gap) - pip_x_border + pip_x_gap, _nOutputHeight - _scaled_height + pip_y_reduce - (_pip_height + pip_y_gap)*(imageIdx / 4), 0, (_scaled_width - _scaled_height) / 2, _pip_width, _pip_height);
 
 				}
 				else if (pFrame->width == _student_height && pFrame->height == _student_height) {
@@ -403,12 +432,38 @@ int CAVTranscoder::open_output_file(const char *filename)
 						continue;
 					}
 					_scaled_frame_h_h->pkt_dts = pFrame->pkt_dts;//pass rotation
-					fillDestFrame(pDstFrame, _scaled_frame_h_h, _teacher_width - (imageIdx % 4 + 1) * (_scaled_height + 5) + 4, _teacher_height - _scaled_height + 3 - (_scaled_height + 1)*(imageIdx / 4), 0, 0, _scaled_height - 3, _scaled_height - 3);
+					fillDestFrame(pDstFrame, _scaled_frame_h_h, _teacher_width - (imageIdx % 4 + 1) * (_pip_width + pip_x_gap) - pip_x_border + pip_x_gap, _nOutputHeight - _scaled_height + pip_y_reduce - (_pip_height + pip_y_gap)*(imageIdx / 4), 0, 0, _pip_width, _pip_height);
 				}
 				else {
-					printf("\nthe frame resolution %dx%d is unexpected! ignored!", pFrame->width, pFrame->height);
+					if (pFrame->width > pFrame->height) {
+						h = pDecoder->scale_frame(pFrame, _scaled_frame_w_h, _scaled_width, _scaled_height);
+						if (h <= 0){
+							printf("\nscale output result:%d?,ignored", h);
+							continue;
+						}
+						_scaled_frame_w_h->pkt_dts = pFrame->pkt_dts;//pass rotation
+						fillDestFrame(pDstFrame, _scaled_frame_w_h, _teacher_width - (imageIdx % 4 + 1) * (_pip_width + pip_x_gap) - pip_x_border + pip_x_gap, _nOutputHeight - _scaled_height + pip_y_reduce - (_pip_height + pip_y_gap)*(imageIdx / 4), (_scaled_width - _scaled_height) / 2, 0, _pip_width, _pip_height);
+					}
+					else if (pFrame->width == pFrame->height)
+					{
+						h = pDecoder->scale_frame(pFrame, _scaled_frame_h_h, _scaled_height, _scaled_height);
+						if (h <= 0){
+							printf("\nscale output result:%d?,ignored", h);
 							continue;
 						}
+						_scaled_frame_h_h->pkt_dts = pFrame->pkt_dts;//pass rotation
+						fillDestFrame(pDstFrame, _scaled_frame_h_h, _teacher_width - (imageIdx % 4 + 1) * (_pip_width + pip_x_gap) - pip_x_border + pip_x_gap, _nOutputHeight - _scaled_height + pip_y_reduce - (_pip_height + pip_y_gap)*(imageIdx / 4), 0, 0, _pip_width, _pip_height);
+					}
+					else {
+						h = pDecoder->scale_frame(pFrame, _scaled_frame_h_w, _scaled_height, _scaled_width);
+						if (h <= 0){
+							printf("\nscale output result:%d?,ignored", h);
+							continue;
+						}
+						_scaled_frame_h_w->pkt_dts = pFrame->pkt_dts;//pass rotation
+						fillDestFrame(pDstFrame, _scaled_frame_h_w, _teacher_width - (imageIdx % 4 + 1) * (_pip_width + pip_x_gap) - pip_x_border + pip_x_gap, _nOutputHeight - _scaled_height + pip_y_reduce - (_pip_height + pip_y_gap)*(imageIdx / 4), 0, (_scaled_width - _scaled_height) / 2, _pip_width, _pip_height);
+					}
+				}
 
 				imageIdx++;
 			}
@@ -508,9 +563,9 @@ int CAVTranscoder::open_output_file(const char *filename)
 				memcpy(pDstFrame->data[0] + (y + i)*pDstFrame->linesize[0] + x, pSrcFrame->data[0] + (i + srcy) * pSrcFrame->linesize[0] + srcx, w);
 			}
 
-			for (int i = 0; i < h / 2; i++){
-				memcpy(pDstFrame->data[1] + (y / 2 + i)*pDstFrame->linesize[1] + x / 2, pSrcFrame->data[1] + (i + srcy / 2) * pSrcFrame->linesize[1] + srcx/2, w / 2);
-				memcpy(pDstFrame->data[2] + (y / 2 + i)*pDstFrame->linesize[2] + x / 2, pSrcFrame->data[2] + (i + srcy / 2) * pSrcFrame->linesize[2] + srcx/2, w / 2);
+			for (int i = 0; i < (h +1) / 2; i++){
+				memcpy(pDstFrame->data[1] + (y / 2 + i)*pDstFrame->linesize[1] + x / 2, pSrcFrame->data[1] + (i + srcy / 2) * pSrcFrame->linesize[1] + srcx/2, (w +1)/ 2);
+				memcpy(pDstFrame->data[2] + (y / 2 + i)*pDstFrame->linesize[2] + x / 2, pSrcFrame->data[2] + (i + srcy / 2) * pSrcFrame->linesize[2] + srcx/2, (w +1)/ 2);
 			}
 		}
 		else if (pSrcFrame->pkt_dts == 180) {
@@ -525,16 +580,16 @@ int CAVTranscoder::open_output_file(const char *filename)
 			}
 			unsigned char * startSrcU = pSrcFrame->data[1] + pSrcFrame->width / 2 + ((pSrcFrame->height - srcy -1)/ 2) * pSrcFrame->linesize[1] - srcx / 2 - 1;
 			unsigned char * startSrcV = pSrcFrame->data[2] + pSrcFrame->width / 2 + ((pSrcFrame->height - srcy -1)/ 2) * pSrcFrame->linesize[2] - srcx / 2 - 1;
-			for (int i = 0; i < h / 2; i++){
+			for (int i = 0; i < (h + 1) / 2; i++){
 				unsigned char * psrc = startSrcU - i * pSrcFrame->linesize[1];
 				unsigned char * pdst = pDstFrame->data[1] + (y / 2 + i)*pDstFrame->linesize[1] + x / 2;
-				unsigned char * pdst_end = pdst + w/2;
+				unsigned char * pdst_end = pdst + (w + 1)/2;
 				for (; pdst < pdst_end; psrc--, pdst++) {
 					*pdst = *psrc;
 				}
 				psrc = startSrcV - i * pSrcFrame->linesize[2];
 				pdst = pDstFrame->data[2] + (y / 2 + i)*pDstFrame->linesize[2] + x / 2;
-				pdst_end = pdst + w/2;
+				pdst_end = pdst + (w +1)/2;
 				for (; pdst < pdst_end; psrc--, pdst++) {
 					*pdst = *psrc;
 				}
@@ -552,9 +607,9 @@ int CAVTranscoder::open_output_file(const char *filename)
 			}
 
 			unsigned char * startSrcU = pSrcFrame->data[1] + srcy/2 * pSrcFrame->linesize[1] + srcx/2;
-			for (int i = 0; i < h/2; i++)	{
+			for (int i = 0; i < (h + 1)/2; i++)	{
 				unsigned char * psrc = startSrcU + i* pSrcFrame->linesize[1];
-				unsigned char * psrc_end = psrc + w/2;
+				unsigned char * psrc_end = psrc + (w +1)/2;
 				unsigned char * pdst = pDstFrame->data[1] + y/2*pDstFrame->linesize[1] + h/2 -1 - i +x/2;
 				for (; psrc < psrc_end; psrc++, pdst += pDstFrame->linesize[1]) {
 					*pdst = *psrc;
@@ -562,9 +617,9 @@ int CAVTranscoder::open_output_file(const char *filename)
 			}
 
 			unsigned char * startSrcV= pSrcFrame->data[2] + srcy / 2 * pSrcFrame->linesize[2] + srcx / 2;
-			for (int i = 0; i < h / 2; i++)	{
+			for (int i = 0; i < (h + 1) / 2; i++)	{
 				unsigned char * psrc = startSrcV + i* pSrcFrame->linesize[2];
-				unsigned char * psrc_end = psrc + w / 2;
+				unsigned char * psrc_end = psrc + (w + 1) / 2;
 				unsigned char * pdst = pDstFrame->data[2] + y / 2 * pDstFrame->linesize[2] + h / 2 -1 - i + x/2;
 				for (; psrc < psrc_end; psrc++, pdst += pDstFrame->linesize[2]) {
 					*pdst = *psrc;
@@ -607,55 +662,55 @@ int CAVTranscoder::open_output_file(const char *filename)
 		}
 
 		if (!_teacherFrame || !_studentFrame) {
-			memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _nOutputHeight);
-			memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _nOutputHeight / 4);
-			memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _nOutputHeight / 4);
+			memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _nOutputHeight);
+			memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _nOutputHeight / 2);
+			memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _nOutputHeight / 2);
 		}
 
 		if (_teacherFrame) {
 			if (_teacherFrame->width == _teacher_width && _teacherFrame->height == _teacher_height) {
 				if (_teacherFrame->pkt_dts != 90){
 					if (_teacher_width < _nOutputWidth) {
-						memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _teacher_height);
-						memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _teacher_height / 4);
-						memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _teacher_height / 4);
+						memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _teacher_height);
+						memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _teacher_height / 2);
+						memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _teacher_height / 2);
 					}
 					fillDestFrame(pDstFrame, _teacherFrame, 0, 0);
 				}
 				else {
 					memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _teacher_height);
-					memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _teacher_height / 4);
-					memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _teacher_height / 4);
+					memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _teacher_height / 2);
+					memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _teacher_height / 2);
 					fillDestFrame(pDstFrame, _teacherFrame, (_nOutputWidth - _teacher_height) / 2, 0, (_teacher_width - _teacher_height) / 2, 0, _teacher_height, _teacher_height);
 				}
 			}
 			else if (_teacherFrame->width == _teacher_height && _teacherFrame->height == _teacher_width) {
 				if (_teacherFrame->pkt_dts == 90){
 					if (_teacher_width < _nOutputWidth) {
-						memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _teacher_height);
-						memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _teacher_height / 4);
-						memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _teacher_height / 4);
+						memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _teacher_height);
+						memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _teacher_height / 2);
+						memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _teacher_height / 2);
 					}
 					fillDestFrame(pDstFrame, _teacherFrame, 0, 0);
 				}
 				else {
-					memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _teacher_height);
-					memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _teacher_height / 4);
-					memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _teacher_height / 4);
+					memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _teacher_height);
+					memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _teacher_height / 2);
+					memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _teacher_height / 2);
 					fillDestFrame(pDstFrame, _teacherFrame, (_nOutputWidth - _teacher_height) / 2, 0, 0, (_teacher_width - _teacher_height) / 2, _teacher_height, _teacher_height);
 				}
 			}
 			else if (_teacherFrame->width == _teacher_height && _teacherFrame->height == _teacher_height) {
-				memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _teacher_height);
-				memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _teacher_height / 4);
-				memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _teacher_height / 4);
+				memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _teacher_height);
+				memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _teacher_height / 2);
+				memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _teacher_height / 2);
 				fillDestFrame(pDstFrame, _teacherFrame, (_nOutputWidth - _teacher_height) / 2, 0);
 			}
 			else {
 				//printf("\nresolution: %dx%d unexpected!", _teacherFrame->width, _teacherFrame->height);
-				memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _teacher_height);
-				memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _teacher_height / 4);
-				memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _teacher_height / 4);
+				memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _teacher_height);
+				memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _teacher_height / 2);
+				memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _teacher_height / 2);
 				
 				fillDestFrame(pDstFrame, _teacherFrame, 0, 0);
 			}
@@ -663,31 +718,31 @@ int CAVTranscoder::open_output_file(const char *filename)
 				if (_studentFrame->width == _student_width) {
 					if (_studentFrame->pkt_dts != 90){
 						if (_student_width < _nOutputWidth) {
-							memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, _nOutputWidth * _student_height);
-							memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, _nOutputWidth * _student_height / 4);
-							memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, _nOutputWidth * _student_height / 4);
+							memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, pDstFrame->linesize[0] * _student_height);
+							memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, pDstFrame->linesize[1] * _student_height / 2);
+							memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, pDstFrame->linesize[2] * _student_height / 2);
 						}
 						fillDestFrame(pDstFrame, _studentFrame, 0, _teacher_height);
 					}
 					else {
-						memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, _nOutputWidth * _student_height);
-						memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, _nOutputWidth * _student_height / 4);
-						memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, _nOutputWidth * _student_height / 4);
+						memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, pDstFrame->linesize[0] * _student_height);
+						memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, pDstFrame->linesize[1] * _student_height / 2);
+						memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, pDstFrame->linesize[2] * _student_height / 2);
 						fillDestFrame(pDstFrame, _studentFrame, (_nOutputWidth - _student_height) / 2, _teacher_height, (_student_width - _student_height) / 2, 0, _student_height, _student_height);
 					}
 				}
 				else if (_studentFrame->pkt_dts == 90){
 					if (_student_width < _nOutputWidth) {
-						memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, _nOutputWidth * _student_height);
-						memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, _nOutputWidth * _student_height / 4);
-						memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, _nOutputWidth * _student_height / 4);
+						memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, pDstFrame->linesize[0] * _student_height);
+						memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, pDstFrame->linesize[1] * _student_height / 2);
+						memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, pDstFrame->linesize[2] * _student_height / 2);
 					}
 					fillDestFrame(pDstFrame, _studentFrame, 0, _teacher_height);
 				}
 				else {
-					memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, _nOutputWidth * _student_height);
-					memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, _nOutputWidth * _student_height / 4);
-					memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, _nOutputWidth * _student_height / 4);
+					memset(pDstFrame->data[0] + _teacher_height * pDstFrame->linesize[0], _blank_y, pDstFrame->linesize[0] * _student_height);
+					memset(pDstFrame->data[1] + _teacher_height / 2 * pDstFrame->linesize[1], _blank_u, pDstFrame->linesize[1] * _student_height / 2);
+					memset(pDstFrame->data[2] + _teacher_height / 2 * pDstFrame->linesize[2], _blank_v, pDstFrame->linesize[2] * _student_height / 2);
 					fillDestFrame(pDstFrame, _studentFrame, (_nOutputWidth - _student_height) / 2, _teacher_height, 0, (_student_width - _student_height) / 2, _student_height, _student_height);
 				}
 			}
@@ -714,9 +769,9 @@ int CAVTranscoder::open_output_file(const char *filename)
 			}
 			else {
 				//printf("\nresolution: %dx%d unexpected!", _studentFrame->width, _studentFrame->height);
-				memset(pDstFrame->data[0], _blank_y, _nOutputWidth * _student_height);
-				memset(pDstFrame->data[1], _blank_u, _nOutputWidth * _student_height / 4);
-				memset(pDstFrame->data[2], _blank_v, _nOutputWidth * _student_height / 4);
+				memset(pDstFrame->data[0], _blank_y, pDstFrame->linesize[0] * _teacher_height);
+				memset(pDstFrame->data[1], _blank_u, pDstFrame->linesize[1] * _teacher_height / 2);
+				memset(pDstFrame->data[2], _blank_v, pDstFrame->linesize[2] * _teacher_height / 2);
 				fillDestFrame(pDstFrame, _studentFrame, 0, 0);
 			}
 		}

@@ -5,7 +5,7 @@
 class CAVTranscoder
 {
 public:
-	CAVTranscoder(bool bOne2One, int width_teacher, int height_teacher, int student_width,int student_height);
+	CAVTranscoder(bool bOne2One, int width_teacher, int height_teacher, int student_width,int student_height, bool has_teacher, int max_audio);
 	virtual ~CAVTranscoder();
 
 	int add(media_info & info);
@@ -46,6 +46,8 @@ private:
 	int _max_audio;
 	int _scaled_width;
 	int	_scaled_height;
+	int _pip_width;
+	int _pip_height;
 	int	_teacher_width;
 	int	_teacher_height;
 	int _student_width;

@@ -42,5 +42,11 @@ V2.0.1
 
 V2.0.2
 1.修改学生视频为320x240，老师的视频为240x180时，老师背景有花屏
-2.修改老师和学生视频都为240x180视频时，视频宽度仍为240, 且有花屏
+2.修改老师和学生视频都为240x180视频时，视频宽度仍为240（由于之前假定只有320x240的视频尺寸), 且有花屏
 3.只有一路视频时，默认合成为上下布局
+
+V2.0.3
+1.没有老师，但是有两个学生时，默认使用一对多布局
+2.一对一时，老师和学生的视频尺寸不同时，合成的视频高度取老师视频高度加上学生视频高度（之前版本假定老师和学生视频大小一致，使用的是最大高度的二倍）
+3.一对多时，支持学生的视频尺寸不一致的情况（之前版本假定只有一种视频尺寸，其它尺寸视为异常）
+4.一对多时，最多只在老师视频下部排4个学生，多于4个学生的情况，扩大合成视频的高度，把学生视频排列在老师视频下方，保证老师视频部分最多只有一排学生视频，避免老师视频被过度遮挡
\ No newline at end of file

@@ -1123,7 +1123,7 @@ int process_av_files(char * record_info, int piptype)
 		}
 	}
 
-	CAVTranscoder videoTranscoder(one2one, width_teacher, height_teacher,width_student, height_student);
+	CAVTranscoder videoTranscoder(one2one, width_teacher, height_teacher,width_student, height_student, has_teacher, max_audio);
 	videoTranscoder.set_max_audio(max_audio);
 
 	int64_t cur_time = 0;