Gasmeat
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Raspberry pi 4 composite out don't working

Tue Sep 10, 2019 4:26 am

Hello. Recently I bought raspberry pi 4. At first It did not want to start, only the red led light was on. According to the instructions, I reprogrammed the EEPROM. Then I was installed Raspbian through NOOBS. I used the HDMI output during installation. After installation, I edited config.txt, uncommenting sdtv_mode = 2. But when connected to a TV via RCA output, the image is missing. Just dark screen. What could be the problem? The cable is 100% working, the ground is where it is needed, on RPI3b+ everything worked with this cable and the same settings. Thanks.

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rpdom
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Re: Raspberry pi 4 composite out don't working

Tue Sep 10, 2019 6:15 am

By default the composite output on the Pi 4 is disabled because it slows the system down. You need to add this to config.txt

Code: Select all

enable_tvout=1
https://www.raspberrypi.org/documentati ... t/video.md
Unreadable squiggle

Gasmeat
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Re: Raspberry pi 4 composite out don't working

Tue Sep 10, 2019 10:29 am

rpdom wrote:
Tue Sep 10, 2019 6:15 am
By default the composite output on the Pi 4 is disabled because it slows the system down.
Will this problem be solved somehow in the future?

jamesh
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Re: Raspberry pi 4 composite out don't working

Tue Sep 10, 2019 10:44 am

Gasmeat wrote:
Tue Sep 10, 2019 10:29 am
rpdom wrote:
Tue Sep 10, 2019 6:15 am
By default the composite output on the Pi 4 is disabled because it slows the system down.
Will this problem be solved somehow in the future?
What do you mean solved? It's not actually a problem. To get composite, you need to add that command to config.txt. That's 'just the way it works'.

(Note, the reason it works this way - composite mode requires some lower clock frequencies, so to have it enabled by default will mean ALL users have to use those lower clock frequencies, so everyone get lower performance)
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Gasmeat
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Re: Raspberry pi 4 composite out don't working

Tue Sep 10, 2019 12:25 pm

jamesh wrote:
Tue Sep 10, 2019 10:44 am
Gasmeat wrote:
Tue Sep 10, 2019 10:29 am
rpdom wrote:
Tue Sep 10, 2019 6:15 am
By default the composite output on the Pi 4 is disabled because it slows the system down.
Will this problem be solved somehow in the future?
What do you mean solved? It's not actually a problem. To get composite, you need to add that command to config.txt. That's 'just the way it works'.

(Note, the reason it works this way - composite mode requires some lower clock frequencies, so to have it enabled by default will mean ALL users have to use those lower clock frequencies, so everyone get lower performance)
system starts extremely slow! there was no such problem on RPI3b+

jamesh
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Re: Raspberry pi 4 composite out don't working

Tue Sep 10, 2019 1:31 pm

Gasmeat wrote:
Tue Sep 10, 2019 12:25 pm
jamesh wrote:
Tue Sep 10, 2019 10:44 am
Gasmeat wrote:
Tue Sep 10, 2019 10:29 am

Will this problem be solved somehow in the future?
What do you mean solved? It's not actually a problem. To get composite, you need to add that command to config.txt. That's 'just the way it works'.

(Note, the reason it works this way - composite mode requires some lower clock frequencies, so to have it enabled by default will mean ALL users have to use those lower clock frequencies, so everyone get lower performance)
system starts extremely slow! there was no such problem on RPI3b+
That's a different thing. The extreme slowness is a bug I am currently looking at, but there is currently no getting around the fact that when using composite we have to clock the system more slowly than when using HDMI, so it WILL run more slowly. Not a huge amount more slowly, but probably noticeable.
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Re: Raspberry pi 4 composite out don't working

Tue Sep 10, 2019 3:19 pm

Github issue for composite issues here..

https://github.com/raspberrypi/firmware/issues/1223
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 2:33 am

Gasmeat wrote:
Tue Sep 10, 2019 4:26 am
Hello. Recently I bought raspberry pi 4. At first It did not want to start, only the red led light was on. According to the instructions, I reprogrammed the EEPROM. Then I was installed Raspbian through NOOBS. I used the HDMI output during installation. After installation, I edited config.txt, uncommenting sdtv_mode = 2. But when connected to a TV via RCA output, the image is missing. Just dark screen. What could be the problem? The cable is 100% working, the ground is where it is needed, on RPI3b+ everything worked with this cable and the same settings. Thanks.
Did you double check your output plugs? If you're using a camcorder cable, you need to reverse the video (yellow) and R audio (red) plugs, because of the wiring of the 4-pole A/V socket. Maybe you had it right on the 3b+, but you didn't make the exact same connections on the 4. See the table in this post, below the picture:

https://www.raspberrypi.org/forums/view ... 04#p714304

Gasmeat
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 4:17 am

jamesh wrote:
Tue Sep 10, 2019 10:44 am
Gasmeat wrote:
Tue Sep 10, 2019 10:29 am
rpdom wrote:
Tue Sep 10, 2019 6:15 am
By default the composite output on the Pi 4 is disabled because it slows the system down.
Will this problem be solved somehow in the future?
What do you mean solved? It's not actually a problem. To get composite, you need to add that command to config.txt. That's 'just the way it works'.

(Note, the reason it works this way - composite mode requires some lower clock frequencies, so to have it enabled by default will mean ALL users have to use those lower clock frequencies, so everyone get lower performance)
maybe off topic, but still: it’s strange why the manufacturer produces a raw product without testing the performance of all components? I use raspberry pi exclusively through composite output on crt tv. and it was a surprise to me that the manufacturer disabled this feature by default, believing that just few people use the RCA output. In this case, they could completely remove it from the board so as not to mislead people

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rpdom
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 6:20 am

Gasmeat wrote:
Wed Sep 11, 2019 4:17 am
maybe off topic, but still: it’s strange why the manufacturer produces a raw product without testing the performance of all components? I use raspberry pi exclusively through composite output on crt tv. and it was a surprise to me that the manufacturer disabled this feature by default, believing that just few people use the RCA output. In this case, they could completely remove it from the board so as not to mislead people
Of course they tested it. How else do you think they know about the clock speeds?

They are probably right that few people use the "RCA output" as the Pi 4B doesn't have an RCA socket. It does have the A/V 3.5mm jack socket with composite video output that is being discussed here, but that won't be used by the majority of users - see sales of the Pi Zero for example - there is no composite video socket on that one, just a two pin header position where you can solder one in if needed.
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Gasmeat
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 6:49 am

rpdom wrote:
Wed Sep 11, 2019 6:20 am
Gasmeat wrote:
Wed Sep 11, 2019 4:17 am
maybe off topic, but still: it’s strange why the manufacturer produces a raw product without testing the performance of all components? I use raspberry pi exclusively through composite output on crt tv. and it was a surprise to me that the manufacturer disabled this feature by default, believing that just few people use the RCA output. In this case, they could completely remove it from the board so as not to mislead people
Of course they tested it. How else do you think they know about the clock speeds?

They are probably right that few people use the "RCA output" as the Pi 4B doesn't have an RCA socket. It does have the A/V 3.5mm jack socket with composite video output that is being discussed here, but that won't be used by the majority of users - see sales of the Pi Zero for example - there is no composite video socket on that one, just a two pin header position where you can solder one in if needed.
so what did you mean by that? just farted into the sky? I don't care what sales pi zero. I want to know why, knowing about the problems with composite output, the manufacturer started selling his product

jamesh
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 6:59 am

Gasmeat wrote:
Wed Sep 11, 2019 6:49 am
rpdom wrote:
Wed Sep 11, 2019 6:20 am
Gasmeat wrote:
Wed Sep 11, 2019 4:17 am
maybe off topic, but still: it’s strange why the manufacturer produces a raw product without testing the performance of all components? I use raspberry pi exclusively through composite output on crt tv. and it was a surprise to me that the manufacturer disabled this feature by default, believing that just few people use the RCA output. In this case, they could completely remove it from the board so as not to mislead people
Of course they tested it. How else do you think they know about the clock speeds?

They are probably right that few people use the "RCA output" as the Pi 4B doesn't have an RCA socket. It does have the A/V 3.5mm jack socket with composite video output that is being discussed here, but that won't be used by the majority of users - see sales of the Pi Zero for example - there is no composite video socket on that one, just a two pin header position where you can solder one in if needed.
so what did you mean by that? just farted into the sky? I don't care what sales pi zero. I want to know why, knowing about the problems with composite output, the manufacturer started selling his product
At launch, composite worked fine, but needed a config.txt entry to enable it. Why is that a problem? It's very slightly different to previous models in that respect, but its not a problem.

Note, the is an issue with the current firmware and composite I am currently looking into.
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Imperf3kt
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 7:01 am

Gasmeat wrote:
Wed Sep 11, 2019 6:49 am
rpdom wrote:
Wed Sep 11, 2019 6:20 am
Gasmeat wrote:
Wed Sep 11, 2019 4:17 am
maybe off topic, but still: it’s strange why the manufacturer produces a raw product without testing the performance of all components? I use raspberry pi exclusively through composite output on crt tv. and it was a surprise to me that the manufacturer disabled this feature by default, believing that just few people use the RCA output. In this case, they could completely remove it from the board so as not to mislead people
Of course they tested it. How else do you think they know about the clock speeds?

They are probably right that few people use the "RCA output" as the Pi 4B doesn't have an RCA socket. It does have the A/V 3.5mm jack socket with composite video output that is being discussed here, but that won't be used by the majority of users - see sales of the Pi Zero for example - there is no composite video socket on that one, just a two pin header position where you can solder one in if needed.
so what did you mean by that? just farted into the sky? I don't care what sales pi zero. I want to know why, knowing about the problems with composite output, the manufacturer started selling his product


Because as was explained, they're not problems, just bugs.
The disabled by default is because most people expect the device to run at full spec, if you want to run at below spec so you can support composite, then you can enable it. It's a small change that meant the majority of users won't have to mess with anything to get their Pi displaying video. The few that do (for example, you) are slightly inconvenienced, but it was one or the other, a few or a majority. Surely the correct decision is obvious.
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davidcoton
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 8:38 am

Imperf3kt wrote:
Wed Sep 11, 2019 7:01 am
Because as was explained, they're not problems, just bugs.
Not even a bug. It's documented, so it's a feature.
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jamesh
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 1:35 pm

Talking of bugs, think we have got to the bottom of the composite problem, which appears to have been introduced when overscan correction was pulled in. There's a couple of PR's going through the system now (GPU firmware AND DRM changes needed), so will be in rpi-update, providing people are happy, in a couple of days.

It has shown up a gap in out test regime, so will try and fill that in as well.
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 3:47 pm

Thanks for the update. It hasn't affected me, but it's good to get a glimpse of your process and the changes an apparently small issue can provoke.

Keep up the bug squashing! Then on to something new? (Yes I know you probably can't/won't answer that :lol: )
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jamesh
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Re: Raspberry pi 4 composite out don't working

Wed Sep 11, 2019 8:08 pm

davidcoton wrote:
Wed Sep 11, 2019 3:47 pm
Thanks for the update. It hasn't affected me, but it's good to get a glimpse of your process and the changes an apparently small issue can provoke.

Keep up the bug squashing! Then on to something new? (Yes I know you probably can't/won't answer that :lol: )
Going to be bug fixing for a while yet I suspect, I'll be concentrating on the HDMI and other video issues - a few people having issues with certain monitors.
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Gasmeat
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Re: Raspberry pi 4 composite out don't working

Sun Sep 15, 2019 10:28 am

jamesh wrote:
Wed Sep 11, 2019 8:08 pm
Going to be bug fixing for a while yet I suspect, I'll be concentrating on the HDMI and other video issues - a few people having issues with certain monitors.
thank you dear friend! it works! now I need to wait for retropie support, but that's another story...

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antiriad
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Re: Raspberry pi 4 composite out don't working

Thu Dec 26, 2019 7:07 am

Hello,
a RPi4 with TV-out enabled will still remain more powerful than a RPi3+?
Thank you

jamesh
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Re: Raspberry pi 4 composite out don't working

Thu Dec 26, 2019 8:01 am

antiriad wrote:
Thu Dec 26, 2019 7:07 am
Hello,
a RPi4 with TV-out enabled will still remain more powerful than a RPi3+?
Thank yous
Correct.
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