Wenn ich Frames aus einer AVI-Datei dekodiere und sie dann in x264 dekodiere und in eine MP4-Datei speichere, sind die fps der Ausgabedatei immer 12.800. Daher wird die Datei sehr schnell abgespielt. Aber wenn ich die in h264 codierten frames im avi format und nicht mp4 speichere, so ist die fps wie ich wollte - 25.

Woran könnte das liegen?

Hier der Code, den ich in VS2010 geschrieben habe:

#include "stdafx.h"
#include "inttypes.h"

extern "C" {
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/avutil.h"
#include <libswscale/swscale.h>
#include <libavutil/opt.h>
#include <libswscale/swscale.h>
#include <libavutil/imgutils.h>
}

#include <iostream>
using namespace std;

int main(int argc, char* argv[])
{
   const char* inFileName = "C:\\000227_C1_GAME.avi";
   const char* outFileName = "c:\\test.avi";
   const char* outFileType = "avi";

   av_register_all();

   AVFormatContext* inContainer = NULL;   
   if(avformat_open_input(&inContainer, inFileName, NULL, NULL) < 0)   
      exit(1);

   if(avformat_find_stream_info(inContainer, NULL) < 0)
      exit(1);

   // Find video stream
   int videoStreamIndex = -1;
   for (unsigned int i = 0; i < inContainer->nb_streams; ++i)
   {
      if (inContainer->streams[i] && inContainer->streams[i]->codec &&
         inContainer->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
      {
         videoStreamIndex = i;
         break;
      }
   }
   if (videoStreamIndex == -1) exit(1);

   AVFormatContext* outContainer = NULL;
   if(avformat_alloc_output_context2(&outContainer, NULL, outFileType, outFileName) < 0)
      exit(1);

   // ---------------------------- 
   // Decoder
   // ---------------------------- 
   AVStream const *const inStream = inContainer->streams[videoStreamIndex];
   AVCodec *const decoder = avcodec_find_decoder(inStream->codec->codec_id);
   if(!decoder) 
      exit(1);
   if(avcodec_open2(inStream->codec, decoder, NULL) < 0) 
      exit(1);

   // ---------------------------- 
   // Encoder
   // ----------------------------             
   AVCodec *encoder = avcodec_find_encoder(AV_CODEC_ID_H264);
   if(!encoder) 
      exit(1);
   AVStream *outStream = avformat_new_stream(outContainer, encoder);      
   if(!outStream)
      exit(1);
   avcodec_get_context_defaults3(outStream->codec, encoder);   

   // Construct encoder
   if(outContainer->oformat->flags & AVFMT_GLOBALHEADER) 
      outStream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;   

   outStream->codec->coder_type = AVMEDIA_TYPE_VIDEO;
   outStream->codec->pix_fmt = AV_PIX_FMT_YUV420P;
   outStream->codec->width = inStream->codec->width;
   outStream->codec->height = inStream->codec->height;
   outStream->codec->codec_id = encoder->id;
   outStream->codec->bit_rate = 500000;
   //outStream->codec->rc_min_rate = 600000;
   //outStream->codec->rc_max_rate = 800000;

   outStream->codec->time_base.den = 25;
   outStream->codec->time_base.num = 1;
   outStream->codec->gop_size = 250; // Keyframe interval(=GOP length). Determines maximum distance distance between I-frames
   outStream->codec->keyint_min = 25; // minimum GOP size
   outStream->codec->max_b_frames = 3;//16; // maximum number of B-frames between non-B-frames
   outStream->codec->b_frame_strategy = 1; // decides the best number of B-frames to use. Default mode in x264.
   outStream->codec->scenechange_threshold = 40;
   outStream->codec->refs = 6; // abillity to reference frames other than the one immediately prior to the current frame. specify how many references can be used.
   outStream->codec->qmin = 0;//10;
   outStream->codec->qmax = 69;//51;
   outStream->codec->qcompress = 0.6;
   outStream->codec->max_qdiff = 4;
   outStream->codec->i_quant_factor = 1.4;//0.71;   

   outStream->codec->refs=1;//3;
   outStream->codec->chromaoffset = -2;
   outStream->codec->thread_count = 1;   
   outStream->codec->trellis = 1;
   outStream->codec->me_range = 16;
   outStream->codec->me_method = ME_HEX; //hex
   outStream->codec->flags2 |= CODEC_FLAG2_FAST;   
   outStream->codec->coder_type = 1;


   if(outStream->codec->codec_id == AV_CODEC_ID_H264)
   {
        av_opt_set(outStream->codec->priv_data, "preset", "slow", 0);
   }

   // Open encoder
   if(avcodec_open2(outStream->codec, encoder, NULL) < 0) 
      exit(1);

   // Open output container
   if(avio_open(&outContainer->pb, outFileName, AVIO_FLAG_WRITE) < 0)
      exit(1);

   //close_o

   AVFrame *decodedFrame = avcodec_alloc_frame();
   if(!decodedFrame) 
      exit(1);
   AVFrame *encodeFrame = avcodec_alloc_frame();
   if(!encodeFrame) 
      exit(1);
   encodeFrame->format = outStream->codec->pix_fmt;
   encodeFrame->width = outStream->codec->width;
   encodeFrame->height = outStream->codec->height;
   if(av_image_alloc(encodeFrame->data, encodeFrame->linesize, 
                 outStream->codec->width, outStream->codec->height, 
                 outStream->codec->pix_fmt, 1) < 0)
      exit(1);

   av_dump_format(inContainer, 0, inFileName,0);

   //Write header to ouput container
   avformat_write_header(outContainer, NULL);

   AVPacket decodePacket, encodedPacket;
   int got_frame, len;
   while(av_read_frame(inContainer, &decodePacket)>=0)
   {      
      if (decodePacket.stream_index == videoStreamIndex)
      {                  
         len = avcodec_decode_video2(inStream->codec, decodedFrame, &got_frame, &decodePacket);
         if(len < 0)
            exit(1);
         if(got_frame)
         {
            av_init_packet(&encodedPacket);
            encodedPacket.data = NULL;
            encodedPacket.size = 0;         
            if(avcodec_encode_video2(outStream->codec, &encodedPacket, decodedFrame, &got_frame) < 0)
               exit(1);
            if(got_frame)
            {
               if (outStream->codec->coded_frame->key_frame)
                  encodedPacket.flags |= AV_PKT_FLAG_KEY;

               encodedPacket.stream_index = outStream->index;

               if(av_interleaved_write_frame(outContainer, &encodedPacket) < 0)
                  exit(1);

               av_free_packet(&encodedPacket);
            }
         }
      }

      av_free_packet(&decodePacket);
   }
   av_write_trailer(outContainer);
   avio_close(outContainer->pb);

   avcodec_free_frame(&encodeFrame);
   avcodec_free_frame(&decodedFrame);

   avformat_free_context(outContainer);
   av_close_input_file(inContainer);
   return 0;
}