Jpeg质量

JPEG本來就是有損壓縮，一定會比BMP畫質有差。
要提升JPEG效果，可以在編碼處修改Q值參數。詳情可見RDK包內的Jpeg encoder usr guide

你好， 谢谢你的回复。
问下怎么修改Q？ 我查看了http://wenku.baidu.com/link?url=eFDqCirAcCkf5tJ8ILeezW0wbrt0H80Nd5u7S4L7LfmnQVLiLgltqegJ5osx-Sf9t76ebE5YGznJpptFnA8aCxdTbaZQV8fuNZo-0SdpjnW 还是没找到怎么修改啊。

########################################################################
# Encoder Control
########################################################################

FrameWidth = 176 # Frame width should be multiple of 16
FrameHeight = 144 # Frame height should be multiple of 16

QualityFactor = 20 # Quality Setting to be used.
# Ranges between 2 and 97.
# 2 => Lowest Quality. 97 => Best Quality.

CaptureWidth = 176 # Image width to compute image pitch.
# If Capture Width is > Image Width then
# use the former for image pitch.
generateHeader = 0 # Set 1 => Generate Header Only
debugTraceLevel = 0 # Specifies the debug trace level
lastNFramesToLog = 0 # Specifies the number of past frames
# to log debug trace. If debugTraceLevel is
# greater than 0, lastNFramesToLog must range
# between 0 and 10.
tilerEnable = 1 # 1 => Luma in TILER8, 0=> Luma in Raw.
chromaTilerMode = 0 # Valid only if tilerEnable = 1
# 1 => Chroma in TILER8, 0 => Chroma in
# TILER16

我使用的是dvrrdk_0.4版本， 我的代码为：
文件  mcfw//src_bios6/links_m3video/iva_enc/encLink_jpeg.c
430 static Int enclink_jpeg_set_dynamic_params(IJPEGVENC_DynamicParams *
431                                            dynamicParams,
432                                            EncLink_AlgDynamicParams *
433                                            algDynamicParams)
434 [
435     *dynamicParams = JPEGVENC_TI_DYNAMICPARAMS;
436     dynamicParams->videnc2DynamicParams.inputWidth =
437         algDynamicParams->inputWidth;
438     dynamicParams->videnc2DynamicParams.inputHeight =
439         algDynamicParams->inputHeight;
440     dynamicParams->videnc2DynamicParams.captureWidth =
441         algDynamicParams->inputPitch;
442     dynamicParams->videnc2DynamicParams.targetBitRate =
443         algDynamicParams->targetBitRate;
444     dynamicParams->videnc2DynamicParams.targetFrameRate =
445         algDynamicParams->targetFrameRate;
446     dynamicParams->videnc2DynamicParams.interFrameInterval =
447         algDynamicParams->interFrameInterval;
448     dynamicParams->videnc2DynamicParams.intraFrameInterval =
449         algDynamicParams->intraFrameInterval;
450     dynamicParams->videnc2DynamicParams.mvAccuracy =
451         algDynamicParams->mvAccuracy;
452     dynamicParams->videnc2DynamicParams.refFrameRate =
453         algDynamicParams->refFrameRate;
454     dynamicParams->videnc2DynamicParams.ignoreOutbufSizeFlag = XDAS_FALSE;
455     
456     return 0;
457 ]   
在函数 EncLinkJPEG_algSetConfig 中有
695         algObj->u.jpegAlgIfObj.dynamicParams.qualityFactor = algObj->algDynamicParams.qpInitI;
设置algObj->u.jpegAlgIfObj.dynamicParams.qualityFactor  是否就可以了？
# Ranges between 2 and 97.
# 2 => Lowest Quality. 97 => Best Quality.
也适用吗？
谢谢。
 

谢谢 你的答复， 我的问题已经解决了。

怎么解决的，分享下啊，谢谢

venc_start()  后
175     VENC_CHN_DYNAMIC_PARAM_S params = [ 0 ];
176     params.qpMin = 97;
177     params.qpMax = 97;
178     params.qpInit = 97;
179     Venc_setDynamicParam(0, 0, ¶ms, VENC_QPVAL_I);
实际上就是设置那个qualityFactor