Hey,
I am decoding an OGG video (theora & vorbis as codecs) and want to show
it on the screen (using Ogre 3D) while playing its sound. I can decode
the image stream just fine and the video plays perfectly with the
correct frame rate, etc.
However, I cannot get the sound to play at all with OpenAL.
Here is how I decode audio packets (in a background thread, the
equivalent works just fine for the image stream of the video file):
|//------------------------------------------------------------------------------
int decodeAudioPacket( AVPacket& p_packet, AVCodecContext*
p_audioCodecContext, AVFrame* p_frame,
FFmpegVideoPlayer* p_player, VideoInfo& p_videoInfo)
{
// Decode audio frame
int got_frame= 0;
int decoded= avcodec_decode_audio4(p_audioCodecContext, p_frame,
&got_frame, &p_packet);
if (decoded< 0)
{
p_videoInfo.error= "Error decoding audio frame.";
return decoded;
}
// Frame is complete, store it in audio frame queue
if (got_frame)
{
int bufferSize= av_samples_get_buffer_size(NULL, p_audioCodecContext->channels, p_frame->nb_samples,
p_audioCodecContext->sample_fmt, 0);
int64_t duration= p_frame->pkt_duration;
int64_t dts= p_frame->pkt_dts;
if (staticOgreLog)
{
staticOgreLog->logMessage("Audio frame bufferSize / duration / dts:"
+ boost::lexical_cast<std::string>(bufferSize) + " /"
+ boost::lexical_cast<std::string>(duration) + " /"
+ boost::lexical_cast<std::string>(dts),
Ogre::LML_NORMAL);
}
// Create the audio frame
AudioFrame* frame= new AudioFrame();
frame->dataSize= bufferSize;
frame->data= new uint8_t[bufferSize];
memcpy(frame->data, p_frame->data, bufferSize);
double timeBase= ((double)p_audioCodecContext->time_base.num) /
(double)p_audioCodecContext->time_base.den;
frame->lifeTime= duration* timeBase;
p_player->addAudioFrame(frame);
}
return decoded;
}
|
So, as you can see, I decode the frame, memcpy it to my own struct,
AudioFrame. Now, when the sound is played, I use these audio frame like
this:
|//------------------------------------------------------------------------------||
int numBuffers= 4;
ALuint buffers[4];
alGenBuffers(numBuffers, buffers);
ALenum success= alGetError();
if(success!= AL_NO_ERROR)
{
CONSOLE_LOG("Error on alGenBuffers :" +
Ogre::StringConverter::toString(success) + alGetString(success));
return;
}
// Fill a number of data buffers with audio from the stream
std::vector<AudioFrame*> audioBuffers;
std::vector<unsigned int> audioBufferSizes;
unsigned int numReturned= FFMPEG_PLAYER->getDecodedAudioFrames(numBuffers,
audioBuffers, audioBufferSizes);
// Assign the data buffers to the OpenAL buffers
for (unsigned int i= 0; i< numReturned; ++i)
{
alBufferData(buffers[i], _streamingFormat, audioBuffers[i],
audioBufferSizes[i], _streamingFrequency);
success= alGetError();
if(success!= AL_NO_ERROR)
{
CONSOLE_LOG("Error on alBufferData :" +
Ogre::StringConverter::toString(success) + alGetString(success)
+ " size:" +
Ogre::StringConverter::toString(audioBufferSizes[i]));
return;
}
}
// Queue the buffers into OpenAL
alSourceQueueBuffers(_source, numReturned, buffers);
success= alGetError();
if(success!= AL_NO_ERROR)
{
CONSOLE_LOG("Error queuing streaming buffers:" +
Ogre::StringConverter::toString(success) + alGetString(success));
return;
}
}
alSourcePlay(_source);|
The format and frequency I give to OpenAL are AL_FORMAT_STEREO16 (it is
a stereo sound stream) and 48000 (which is the sample rate of the
AVCodecContext of the audio stream).
And during playback, I do the following to refill OpenAL's buffers:
|//------------------------------------------------------------------------------||||
ALint numBuffersProcessed;
// Check if OpenAL is done with any of the queued buffers
alGetSourcei(_source, AL_BUFFERS_PROCESSED, &numBuffersProcessed);
if(numBuffersProcessed<= 0)
return;
// Fill a number of data buffers with audio from the stream
std::vector<AudiFrame*> audioBuffers;
std::vector<unsigned int> audioBufferSizes;
unsigned int numFilled=
FFMPEG_PLAYER->getDecodedAudioFrames(numBuffersProcessed, audioBuffers,
audioBufferSizes);
// Assign the data buffers to the OpenAL buffers
ALuint buffer;
for (unsigned int i= 0; i< numFilled; ++i)
{
// Pop the oldest queued buffer from the source,
// fill it with the new data, then re-queue it
alSourceUnqueueBuffers(_source, 1, &buffer);
ALenum success= alGetError();
if(success!= AL_NO_ERROR)
{
CONSOLE_LOG("Error Unqueuing streaming buffers:" +
Ogre::StringConverter::toString(success));
return;
}
alBufferData(buffer, _streamingFormat, audioBuffers[i],
audioBufferSizes[i], _streamingFrequency);
success= alGetError();
if(success!= AL_NO_ERROR)
{
CONSOLE_LOG("Error on re- alBufferData:" +
Ogre::StringConverter::toString(success));
return;
}
alSourceQueueBuffers(_source, 1, &buffer);
success= alGetError();
if(success!= AL_NO_ERROR)
{
CONSOLE_LOG("Error re-queuing streaming buffers:" +
Ogre::StringConverter::toString(success) + ""
+ alGetString(success));
return;
}
}
// Make sure the source is still playing,
// and restart it if needed.
ALint playStatus;
alGetSourcei(_source, AL_SOURCE_STATE, &playStatus);
if(playStatus!= AL_PLAYING)
alSourcePlay(_source);|
As you can see, I do quite heavy error checking. But I do not get any
errors. But the only thing that plays is a constant clicking noise.
The video itself is not broken, it can be played fine on any player.
OpenAL can also play *.way files just fine in the same application, so
it is also working.
Any ideas what could be wrong here or how to do this correctly?
My only guess is that somehow, FFmpeg's decode function does not produce
data OpenGL can read. But this is as far as the FFmpeg decode example
goes, so I don't know what's missing. As I understand it, the
decode_audio4 function decodes the frame to raw data. And OpenAL should
be able to work with RAW data (or rather, doesn't work with anything else).
P.S: You can also find this question on StackOverflow, figured it
wouldn't hurt to ask on multiple places:
http://stackoverflow.com/questions/21386135/ffmpeg-openal-playback-streaming-sound-from-video-wont-work
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