#315 No streams found error -libavcodec/libavformat

open
nobody
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5
2005-07-19
2005-07-19
tbc++
No

I'm compiling this program in Ubuntu Linux:

// avcodec_sample.cpp

// A small sample program that shows how to use
libavformat and libavcodec to
// read video from a file.
//
// Use
//
// g++ -o avcodec_sample avcodec_sample.cpp -lavformat
-lavcodec -lz
//
// to build (assuming libavformat and libavcodec are
correctly installed on
// your system).
//
// Run using
//
// avcodec_sample myvideofile.mpg
//
// to write the first five frames from
"myvideofile.mpg" to disk in PPM
// format.

#include <avcodec.h>
#include <avformat.h>

#include <stdio.h>

bool GetNextFrame(AVFormatContext *pFormatCtx,
AVCodecContext *pCodecCtx,
int videoStream, AVFrame *pFrame)
{
static AVPacket packet;
static int bytesRemaining=0;
static uint8_t *rawData;
static bool fFirstTime=true;
int bytesDecoded;
int frameFinished;

// First time we're called, set packet.data to NULL
to indicate it
// doesn't have to be freed
if(fFirstTime)
{
fFirstTime=false;
packet.data=NULL;
}

// Decode packets until we have decoded a complete
frame
while(true)
{
// Work on the current packet until we have
decoded all of it
while(bytesRemaining > 0)
{
// Decode the next chunk of data

bytesDecoded=avcodec_decode_video(pCodecCtx, pFrame,
&frameFinished, rawData, bytesRemaining);

// Was there an error?
if(bytesDecoded < 0)
{
fprintf(stderr, "Error while decoding
frame\n");
return false;
}

bytesRemaining-=bytesDecoded;
rawData+=bytesDecoded;

// Did we finish the current frame? Then we
can return
if(frameFinished)
return true;
}

// Read the next packet, skipping all packets
that aren't for this
// stream
do
{
// Free old packet
if(packet.data!=NULL)
av_free_packet(&packet);

// Read new packet
if(av_read_packet(pFormatCtx, &packet)<0)
goto loop_exit;
} while(packet.stream_index!=videoStream);

bytesRemaining=packet.size;
rawData=packet.data;
}

loop_exit:

// Decode the rest of the last frame
bytesDecoded=avcodec_decode_video(pCodecCtx,
pFrame, &frameFinished,
rawData, bytesRemaining);

// Free last packet
if(packet.data!=NULL)
av_free_packet(&packet);

return frameFinished!=0;
}

void SaveFrame(AVFrame *pFrame, int width, int height,
int iFrame)
{
FILE *pFile;
char szFilename[32];
int y;

// Open file
sprintf(szFilename, "frame%d.ppm", iFrame);
pFile=fopen(szFilename, "wb");
if(pFile==NULL)
return;

// Write header
fprintf(pFile, "P6 %d %d 255\n", width, height);

// Write pixel data
for(y=0; y<height; y++)
fwrite(pFrame->data[0]+y*pFrame->linesize[0],
1, width*3, pFile);

// Close file
fclose(pFile);
}

int main(int argc, char *argv[])
{
AVFormatContext *pFormatCtx;
int i, videoStream;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame;
AVFrame *pFrameRGB;
int numBytes;
uint8_t *buffer;

// Register all formats and codecs
av_register_all();

// Open video file
if(av_open_input_file(&pFormatCtx, argv[1], NULL,
0, NULL)!=0)
return -1; // Couldn't open file

// Retrieve stream information
if(av_find_stream_info(pFormatCtx)<0)
return -1; // Couldn't find stream information

// Dump information about file onto standard error
dump_format(pFormatCtx, 0, argv[1], false);

// Find the first video stream
videoStream=-1;
for(i=0; i<pFormatCtx->nb_streams; i++)

if(pFormatCtx->streams[i]->codec.codec_type==CODEC_TYPE_VIDEO)
{
videoStream=i;
break;
}
if(videoStream==-1)
return -1; // Didn't find a video stream

// Get a pointer to the codec context for the video
stream
pCodecCtx=&pFormatCtx->streams[videoStream]->codec;

// Find the decoder for the video stream
pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
if(pCodec==NULL)
return -1; // Codec not found

// Inform the codec that we can handle truncated
bitstreams -- i.e.,
// bitstreams where frame boundaries can fall in
the middle of packets
if(pCodec->capabilities & CODEC_CAP_TRUNCATED)
pCodecCtx->flags|=CODEC_FLAG_TRUNCATED;

// Open codec
if(avcodec_open(pCodecCtx, pCodec)<0)
return -1; // Could not open codec

// Hack to correct wrong frame rates that seem to
be generated by some
// codecs
if(pCodecCtx->frame_rate>1000 &&
pCodecCtx->frame_rate_base==1)
pCodecCtx->frame_rate_base=1000;

// Allocate video frame
pFrame=avcodec_alloc_frame();

// Allocate an AVFrame structure
pFrameRGB=avcodec_alloc_frame();
if(pFrameRGB==NULL)
return -1;

// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(PIX_FMT_RGB24,
pCodecCtx->width,
pCodecCtx->height);
buffer=new uint8_t[numBytes];

// Assign appropriate parts of buffer to image
planes in pFrameRGB
avpicture_fill((AVPicture *)pFrameRGB, buffer,
PIX_FMT_RGB24,
pCodecCtx->width, pCodecCtx->height);

// Read frames and save first five frames to disk
i=0;
while(GetNextFrame(pFormatCtx, pCodecCtx,
videoStream, pFrame))
{
img_convert((AVPicture *)pFrameRGB,
PIX_FMT_RGB24, (AVPicture*)pFrame,
pCodecCtx->pix_fmt, pCodecCtx->width,
pCodecCtx->height);

// Save the frame to disk
if(++i<=5)
SaveFrame(pFrameRGB, pCodecCtx->width,
pCodecCtx->height, i);
}

// Free the RGB image
delete [] buffer;
av_free(pFrameRGB);

// Free the YUV frame
av_free(pFrame);

// Close the codec
avcodec_close(pCodecCtx);

// Close the video file
av_close_input_file(pFormatCtx);

return 0;
}

The line that dumps file info works great. However,
when the file is loaded, it cannot be played because
pFormatCtx->nb_streams shows zero streams! This happens
with several different files.

Discussion

  • Logged In: NO

    Hmm, I have problem with "No streams found" with .mov file

     
  • This Sourceforge bug tracker here has been abandoned many years ago.

    Our new tracker can be found through http://www.ffmpeg.org/bugreports.html