Hello
I want to write a programm to convert a video. (for example from .mpg to
.flv)
I started with analysing the libavformat/output-example.c file.
This programm creates his own video and saves it in the file from the
parameter.
But I want to convert a video.
Now I add a second parameter.
Something like that....
./output-example in.mpg out.flv
I saw a tutorial about a programm that reads a video (but this is old and
throws exceptions).
Now I changed the Code and I got an exception during the runtime (when i
open the stream).
This is the relevant code from the main-methode:
const char *filenameOut;
const char *filenameIn;
AVOutputFormat *avOutputFmt;
AVFormatContext *oc;
AVFormatContext *avFmtCtxIn;
AVStream *audio_st, *video_st;
double audio_pts, video_pts;
int i;
int videoStream;
AVCodecContext *avCodecCtx;
AVCodec *avCodec;
/* Initialize libavcodec, and register all codecs and formats. */
av_register_all();
if (argc != 3) {
printf("usage: %s input_file output_file\n"
"API example program to output a media file with
libavformat.\n"
"The output format is automatically guessed according to the
file extension.\n"
"Raw images can also be output by using '%%d' in the
filename\n"
"\n", argv[0]);
return 1;
}
filenameIn=argv[1];
filenameOut = argv[2];
// Open video file
if(avformat_open_input(&avFmtCtxIn, filenameIn, NULL, NULL)!=0)
fprintf(stderr, "Couldn't open file\n");// Couldn't open file
// Retrieve stream information
if(avformat_find_stream_info(avFmtCtxIn,NULL)<0)
fprintf(stderr, "Couldn't find stream information\n"); // Couldn't
find stream information
fprintf(stdout, "I found the file. Now I search for the stream\n");
// Find the first video stream
videoStream=-1;
for(i=0; i<avFmtCtxIn->nb_streams; i++)
{
if(avFmtCtxIn->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
{
videoStream=i;
break;
}
}
if(videoStream==-1)
fprintf(stderr, "Couldn't find a video stream\n"); // Didn't find a
video stream
fprintf(stdout, "I find the stream\n");
/* Autodetect the output format from the name. default is MPEG. */
avOutputFmt = av_guess_format(NULL, filenameOut, NULL);
if (!avOutputFmt) {
printf("Could not deduce output format from file extension: using
MPEG.\n");
avOutputFmt = av_guess_format("mpeg", NULL, NULL);
}
if (!avOutputFmt) {
fprintf(stderr, "Could not find suitable output format\n");
return 1;
}
/* Allocate the output media context. */
oc = avformat_alloc_context();
if (!oc) {
fprintf(stderr, "Memory error\n");
return 1;
}
oc->oformat = avOutputFmt;
snprintf(oc->filename, sizeof(oc->filename), "%s", filenameOut);
/* Add the audio and video streams using the default format codecs
* and initialize the codecs. */
//here i set the video-stream (I hope this is a possible way)
video_st = avFmtCtxIn->streams[videoStream];//NULL;
fprintf(stdout, "I set the videostream\n");
audio_st = NULL;
/*if (avOutputFmt->video_codec != CODEC_ID_NONE) {
video_st = add_video_stream(oc, avOutputFmt->video_codec);
}
if (avOutputFmt->audio_codec != CODEC_ID_NONE) {
audio_st = add_audio_stream(oc, avOutputFmt->audio_codec);
}*/
/* Now that all the parameters are set, we can open the audio and
* video codecs and allocate the necessary encode buffers. */
if (video_st)
open_video(oc, video_st); //In this line the error occurs
The Error message is No codec provided to avcodec_open2().
I hope you understand my problem.
Please, help me.
Thanks Bernhard
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