On 2/25/13, Brad O'Hearne <[email protected]> wrote: > > On Feb 18, 2013, at 3:50 PM, Carl Eugen Hoyos <[email protected]> wrote: > >> While I have _no_ idea what the "flv audio codec" could >> be, please use either the aconvert filter or libswresample >> directly to convert from one audio format to another. > > This has turned out to be much more difficult than expected. To review, I'm > trying to take samples captured from QTKit (Apple's QuickTime library) and > resample them to an appropriate format for streaming with FFmpeg. The audio > data received from QTKit capture is a data structured contained within > QTSampleBuffer, which has the following description: > > Linear PCM, 32 bit little-endian floating point, 2 channels, 44100 Hz > > After reading various ffmpeg source, it appears that this maps to the > AV_SAMPLE_FMT_FLT sample format (though note I've also tried > AV_SAMPLE_FMT_FLTP -- with the same result). The output sample format that I > need to resample to is AV_SAMPLE_FMT_S16. > > I have successfully created the resample context, allocated both source and > destination data arrays, and filled the source array with the QTSampleBuffer > data. But the actual conversion is failing, specifically the line: > > // convert to destination format > returnVal = swr_convert(resamplerCtx, > &destinationData, > destinationNumberOfSamples, > (const uint8_t **)&sourceData, > sourceNumberOfSamples); > > is completely crashing the app with an EXC_ARITHMETIC error, which is > generally an indication of a divide by zero error. I have attached a more > extensive code snippet so that you can see how I've gone about this. Note > I've changed sample formats, changed between default (0) and no alignment > (1) on the data array allocations, with no change -- the conversion still > fails. In the call above, both the destination and source number of samples > are 512, the same number of samples that are coming over on the > QTSampleBuffer object. > > Does anyone have any idea what might be causing this? The app is just > outright crashing inside the swr_convert function, giving me almost no clue > what the problem is.
Without looking at exact code I'm playing lottery here. > > Help is greatly appreciated! > > Thanks, > > Brad > > _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
