On Sat, Jun 17, 2023 at 2:48 PM Michael Niedermayer <mich...@niedermayer.cc> wrote:
> Hi > > On Sat, Jun 17, 2023 at 01:08:45PM +0200, Paul B Mahol wrote: > [...] > > > But the biggest issue is your claim of demultiplexing, which your code > does > > not do, its done by called library. > > libsoapy is used just as a thin and common interface to the SDR hardware > > If you comment all uses of libsoapy out and use a file, it will still work. > To be clear, you can dump a raw file with the "-dumpurl" option and > lets say dump the radio spectrum from 6mhz to 16mhz (thats 40mbyte per > second) > and sdrfile with no libsoapy (if you comment that out) will play all AM > radio > stations from that range from just that file. That might be 10 or many more > from the single input stream. > Neither the SDR hardware nor libsoapy have split the radio stations in that > 40mbyte/sec stream. Its basically just raw data from the hardware analog > digital > converter(s). > > The way SDR HW works is very simple. It has an antena an amplifer and at > that > point it might have 1khz to 6ghz of spectrum. > that is then run through a mixer or 2 to shift the part of the spectrum one > is interested in, into the lower frequencies (where its easier to work > with) > and that is then run through a low pass filter and 1 or 2 analog digital > converters and their output goes over your favorte USB cable into sdrdemux > > that time domain signal that sdrdemux/sdrfile then gets is then analyzed in > sdrdemux to find all radio stations and then depending on how its > configured > it will demodulate one or all. > > > > > > The correct place for this code is in libavfilter. Where user could > select > > Besides that sematically its the wrong place (as i said in my previous > reply) > libavfilter is technically wrong too > > sdrdemux for DAB will return a AVStream with digital compressed AAC > sdrdemux for DVB will return a AVStream with digital compressed H.264 or > MPEG2 video > > AVFilter has no support for digital compressed output. > > In fact really what sdrdemux will output is quite similar to what a > matroska demuxer > would, its a bunch of compressed and uncompressed streams, video and audio. > That does not fit in avfilter. > And you dont want it hacked into libavfilter either. > One would want to use the AAC and h.264 streams losslessly, maybe store > them in > a matroska file but avfilter can only handle decompressed audio and video. > > Thank you for your comments! > Even if all that true above, which isn't. Your solution is using seek hack that should be removed. Which library handles compressed stuff? > > [...] > > -- > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB > > Those who are best at talking, realize last or never when they are wrong. > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
