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fsphil / hacktv

Analogue TV transmitter for the HackRF
GNU General Public License v3.0
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AUDIO SYSTER does not encode audio #36

Closed vanhoteen closed 5 years ago

vanhoteen commented 5 years ago

I'm happy with the software, but it encodes the video but the audio does not. I have tried several mp2, mp4, acc, ac3, mp3 files I have ubuntu and hackrf. Can you help me?

vanhoteen@ubuntu:~$ hacktv -m g -f 583000000 -g 47 /home/vanhoteen/Vídeos/canalplus1990.mp4 -r --syster Video: 832x576 25.00 fps (full frame 1024x625) Sample rate: 16000000 UOpening '/home/vanhoteen/Vídeos/canalplus1990.mp4'... Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/vanhoteen/Vídeos/canalplus1990.mp4': Metadata: major_brand : mp42 minor_version : 0 compatible_brands: isommp42 creation_time : 2015-08-28T06:01:56.000000Z Duration: 00:02:39.57, start: 0.000000, bitrate: 318 kb/s U Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 480x360 [SAR 1:1 DAR 4:3], 219 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc (default) Metadata: handler_name : VideoHandler Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 95 kb/s (default) Metadata: creation_time : 2015-08-28T06:01:56.000000Z handler_name : IsoMedia File Produced by Google, 5-11-2011 Using video stream 0. Using audio stream 1.

fsphil commented 5 years ago

Do you get audio without the --syster option?

vanhoteen commented 5 years ago

if I have audio but it is not encrypted, it sounds perfect not like when it goes through the system nagra

fsphil commented 5 years ago

Your decoder is probably expecting the audio to have been inverted. hacktv doesn't do this yet.

vanhoteen commented 5 years ago

thanks ,I thought that if, seeing that video https://youtu.be/CML8Hr_eFZ8 , sorry my answer was late I was sick

shafau commented 5 years ago

Hello, together with @Zcooger help, we've managed to encrypt the audio directly in ffmpeg :) Precise command-line will be posted soon. Now @Zcooger is trying to improve the commands to be 100% accurate and lossless. It should be added direct to hacktv, because prepared audio (in Cryptimage or Audacity or ffmpeg) after demodulation by decoder is some kind of "waving" (loses bass sinusoidally etc.)

Zcooger commented 5 years ago

@shafau Waving sound volume is caused by sample rate differences between the video clock and the modulated audio. It has somehow to be synchronized, Nagravision terminal synchronizes the audio chip with video line rate. @fsphil Where in the code is the most suitable place to oscillate the PCM samples? I have function that modulates the audio signal.

fsphil commented 5 years ago

Just after the call to _av_read_audio in video.c.

Don't exclude the possibility that the inversion frequency is not exactly 12.8 kHz, a slight offset could cause the beating mentioned.

shafau commented 5 years ago

For now we have got something like that: ffmpeg -i input.wav -f lavfi -i "sine=frequency=12800" -filter_complex "[1]volume=+18.064dB[sine];[0][sine]amultiply[mixed];[mixed]lowpass=f=12800" output.wav

We don't know what to do next and how insert that into hacktv

captainjack64 commented 5 years ago

If you have to use ffmpeg then you'd need an ffmpeg audio filter implemented in HackTV. It's probably better to do this post ffmpeg...

fsphil commented 5 years ago

I've added support for audio inversion, use the --systeraudio flag to enable it.