When I decode frames from avi file and then decode them in x264 and save to mp4
file, the fps of the output file is always 12,800. Therefore the file is played
very fast.
What could be the problem?
Thank you
const char* inFileName = "C:\\000227_C1_GAME.avi";
const char* outFileName = "c:\\test.mp4";
const char* outFileType = "mp4";
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 = 400000;
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 = 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 = 10;
outStream->codec->qmax = 51;
outStream->codec->i_quant_factor = 0.71;
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);
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);
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