Re: [Discuss-gnuradio] Generating constant bitrate videos for GNU-RADIO ISDB-T transmission

[Gastón Morales]

Hello Ron,     

We are  aware of the muxrate option to set the correct bitrate for the transmission, but still we are having problems with the reception.  

We use the following command:

ffmpeg -i prueba.webm -c:v mpeg2video -b:v 2M -r ntsc -s 1920x1080 -c:a aac -b:a 64k -f mpegts -mpegts_service_id 0x70e0 -mpegts_flags 'latm' -pes_payload_size 188 -metadata service_name="Brotola" -muxrate 5727280 camara13seg.ts

Do you know if there is anything wrong in this command, or if there is anything to add to make it work properly?

We would really appreciate if you could share us the ffmpeg command that you used in any of your examples. 

Thanks for your prompt response!

El 03/10/19 a las 18:53, Ron Economos escribió:

To create a constant rate transport stream with ffmpeg, you have to use the -muxrate parameter. The video stream does not have to be CBR. However, the peak video rate plus the audio rate cannot exceed the muxrate.

BTW, w6rz.net is my website. Most of the main page streams are muxed at the ATSC rate of 19.392658 Mbps.

Ron

On 10/3/19 14:20, Gastón Morales wrote:

Dear all,

We are a team of engineer students, working on a ISDB-T Digital TV Transmitter for GNU-Radio.
To test the TX, we need to create constant bit rate transport streams that are compatible with the ISDB-T standard.
Currently we are working with ffmpeg to transcode the videos that we want to send, but we are having some issues with the receptor, and we suspect that the videos that we are transcoding with ffmpeg are not constant bit rate videos.
We found the webpage http://www.w6rz.net that has some CBR samples taken out from DVB-T trasmissions. 
Does anyone know how were those samples generated to mantain a constant bit rate?

Thank you!!
 
 

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