From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id A86E54675F for ; Sat, 17 Jun 2023 12:48:53 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id E3F4268C37F; Sat, 17 Jun 2023 15:48:49 +0300 (EEST) Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [217.70.183.197]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id DC8FA68C02A for ; Sat, 17 Jun 2023 15:48:43 +0300 (EEST) X-GND-Sasl: michael@niedermayer.cc Received: by mail.gandi.net (Postfix) with ESMTPSA id 3EDCE1C0005 for ; Sat, 17 Jun 2023 12:48:43 +0000 (UTC) Date: Sat, 17 Jun 2023 14:48:42 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20230617124842.GN1391451@pb2> References: <20230616222048.6562-1-michael@niedermayer.cc> <20230616222048.6562-6-michael@niedermayer.cc> <20230617084627.GM1391451@pb2> MIME-Version: 1.0 In-Reply-To: X-Spam-Flag: yes X-Spam-Level: ************ X-GND-Spam-Score: 180 X-GND-Status: SPAM Subject: Re: [FFmpeg-devel] [PATCH 5/5] avformat: add sdr support X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Type: multipart/mixed; boundary="===============1264666599575533184==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============1264666599575533184== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="LMNJpGI8JQ70mkZF" Content-Disposition: inline --LMNJpGI8JQ70mkZF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 do= es > 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 seco= nd) and sdrfile with no libsoapy (if you comment that out) will play all AM rad= io stations from that range from just that file. That might be 10 or many more =66rom 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 di= gital converter(s). The way SDR HW works is very simple. It has an antena an amplifer and at th= at 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. >=20 > 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 repl= y) 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 MP= EG2 video AVFilter has no support for digital compressed output. In fact really what sdrdemux will output is quite similar to what a matrosk= a 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 the= m in a matroska file but avfilter can only handle decompressed audio and video. Thank you for your comments! [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who are best at talking, realize last or never when they are wrong. --LMNJpGI8JQ70mkZF Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEIAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCZI2rpQAKCRBhHseHBAsP q0AtAJ42BLYvec8qT99zLtvktacWPH3w5QCfU8krVESffSUMZXyBJZ0lnPWdZwM= =isSj -----END PGP SIGNATURE----- --LMNJpGI8JQ70mkZF-- --===============1264666599575533184== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". --===============1264666599575533184==--