[coreVideoEncoder] Go back to fake constant frame rate mode, derive F…

…PS from time base when it matches a standard one Some video encoders like HEVC NVENC don't handle time base not being equal the inverse of frame rate well. This patch tries to fix in particular an extremely low output bitrate with HEVC NVENC and fallback time base of 1/90000 which Avidemux chooses for most variable frame rate source videos.
mean00 · Dec 2, 2020 · 388aa89 · 388aa89
1 parent 85bc8a7
commit 388aa89
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Showing 3 changed files with 70 additions and 21 deletions.
diff --git a/avidemux_core/ADM_coreVideoEncoder/include/ADM_coreVideoEncoder.h b/avidemux_core/ADM_coreVideoEncoder/include/ADM_coreVideoEncoder.h
@@ -77,6 +77,7 @@ virtual        uint64_t    getEncoderDelay(void){return encoderDelay;}
                uint64_t    lastDts; //
 };
 ADM_COREVIDEOENCODER6_EXPORT bool usSecondsToFrac(uint64_t useconds, int *n, int *d, int maxclock=0xFFFF); // mpeg4 allows a maximum of 1<<16-1 as time base
+ADM_COREVIDEOENCODER6_EXPORT bool isStdFrameRate(int &frameRateNum, int &frameRateDen);
 ADM_COREVIDEOENCODER6_EXPORT bool ADM_pluginGetPath(const std::string& pluginName,int pluginVersion,std::string &rootPath);
 ADM_COREVIDEOENCODER6_EXPORT bool ADM_pluginInstallSystem(const std::string& pluginName,const std::string& ext,int pluginVersion);
 ADM_COREVIDEOENCODER6_EXPORT bool ADM_listFile(const std::string& path,const std::string& extension,vector <std::string > & list);

diff --git a/avidemux_core/ADM_coreVideoEncoder/src/ADM_coreVideoEncoder.cpp b/avidemux_core/ADM_coreVideoEncoder/src/ADM_coreVideoEncoder.cpp
@@ -110,6 +110,42 @@ bool usSecondsToFrac(uint64_t useconds, int *n, int *d, int limit)
     return true;
 }
 
+/**
+    \fn stdFrameRate
+    \brief Check that given num/den pair matches a known standard frame rate
+*/
+bool isStdFrameRate(int &frameRateNum, int &frameRateDen)
+{
+    if(frameRateNum < 1 || frameRateDen < 1)
+        return false;
+    int nn,dd;
+#define MAX_CLOCK 180000
+#define MAX_FPS 60
+    if(!av_reduce(&nn, &dd, frameRateNum, frameRateDen, MAX_CLOCK))
+        return false;
+    if(dd != 1 && dd != 1001)
+        return false;
+    if(nn/dd > MAX_FPS)
+        return false;
+    if(dd == 1)
+    {
+        dd*=1000;
+        nn*=1000;
+    }
+    int nb=sizeof(fpsTable)/sizeof(TimeIncrementType);
+    for(int i=0;i<nb;i++)
+    {
+        TimeIncrementType *t=fpsTable+i;
+        if(t->d == nn && t->n == dd)
+        {
+            frameRateNum = nn;
+            frameRateDen = dd;
+            return true;
+        }
+    }
+    return false;
+}
+
 /**
     \fn getRealPtsFromInternal
     \brief Lookup in the stored value to get the exact pts from the truncated one

diff --git a/avidemux_core/ADM_coreVideoEncoder/src/ADM_coreVideoEncoderFFmpeg.cpp b/avidemux_core/ADM_coreVideoEncoder/src/ADM_coreVideoEncoderFFmpeg.cpp
@@ -26,8 +26,6 @@ extern "C"
 char *av_strdup(const char *s);
 void *av_malloc(size_t size) ;
 }
-//#define TIME_TENTH_MILLISEC
-#define USE_REAL_TIME_BASE
 #if 1
     #define aprintf(...) {}
 #else
@@ -341,27 +339,41 @@ bool ADM_coreVideoEncoderFFmpeg::setupInternal(AVCodec *codec)
     prolog(image);
 
     FilterInfo *info=source->getInfo();
-#if defined(TIME_TENTH_MILLISEC)
-    _context->time_base.num=1;
-    _context->time_base.den=10000LL;
-#elif defined(USE_REAL_TIME_BASE)
-    int n = timeScalerNum = info->timeBaseNum & 0x7FFFFFFF;
-    int d = timeScalerDen = info->timeBaseDen & 0x7FFFFFFF;
-    ADM_assert(timeScalerNum);
-    ADM_assert(timeScalerDen);
-    if(codec->id == AV_CODEC_ID_MPEG4)
-        av_reduce(&n,&d,timeScalerNum,timeScalerDen,0xFFFF);
-    _context->time_base.num=n;
-    _context->time_base.den=d;
-#else
-    int n,d;
-    usSecondsToFrac(info->frameIncrement,&n,&d);
-    _context->time_base.num=n;
-    _context->time_base.den=d;
-#endif
+    int n = info->timeBaseNum & 0x7FFFFFFF;
+    int d = info->timeBaseDen & 0x7FFFFFFF;
+    ADM_assert(n);
+    ADM_assert(d);
+    if(isStdFrameRate(d,n))
+    {
+        _context->time_base.num = _context->framerate.den = n;
+        _context->time_base.den = _context->framerate.num = d;
+    }else
+    {
+        int maxClockFreq = 0x7FFFFFFF;
+        switch(codec->id)
+        {
+            case AV_CODEC_ID_MPEG4:
+                maxClockFreq = 0xFFFF;
+                break;
+            case AV_CODEC_ID_MPEG2VIDEO:
+                maxClockFreq = 90000;
+                break;
+            default:break;
+        }
+        usSecondsToFrac(info->frameIncrement,&n,&d,maxClockFreq);
+        _context->time_base.num = _context->framerate.den = n;
+        _context->time_base.den = _context->framerate.num = d;
+        if(codec->id == AV_CODEC_ID_MPEG2VIDEO && !isStdFrameRate(d,n))
+        {
+            ADM_error("Non-standard frame rate %d/%d is not supported for mpeg2video.\n",d,n);
+            return false;
+        }
+    }
     timeScalerNum=_context->time_base.num;
     timeScalerDen=_context->time_base.den;
-   printf("[ff] Time base %d/%d\n", _context->time_base.num,_context->time_base.den);
+    printf("[ff] Time base: %d/%d, frame rate: %d/%d\n",
+        _context->time_base.num, _context->time_base.den,
+        _context->framerate.num, _context->framerate.den);
    if(_hasSettings && LAVS(MultiThreaded))
     {
         encoderMT();