What should you do if the surveillance footage has no sound? First, distinguish whether it was recorded or not aired; ninety percent of the time is stuck at the first step

Last month, my orange cat knocked the water cup off the desk. I watched the replay at work to hear how loud that crisp sound was. The footage clearly showed the cup being smashed, with no sound at all. The first reaction was that the camera was broken, and the second was to return it. Later, after checking three apps, I realized the machine was really good—I had two switches I hadn't even turned on myself. This article will review the inspection order: if your home surveillance is silent, there's a 90% chance you'll find a connection in this article.

first clarify the three matters, otherwise it's all for nothing

the video has no sound, it's actually three completely different illnesses. Mixing them together can make people dizzy :

the first line of this sheet is the most tricky one. At first, I looked it up in reverse, first suspecting the speakers, then adjusting the volume for a long time. Later, I realized my unit didn't record sound at all during video recording—sound isn't just freed from the screen; you have to keep the recording switch on to write to the memory. In other words, having no sound during playback doesn't necessarily mean "no sound can be played"; it could mean "it wasn't recorded back then." The methods for these two amendments are completely different.

By the way, if your home surveillance can't find any footage from a certain day along with the footage or sound, that's a different matter—most likely the loop overwrite has been squeezed out. I previously did the math in the about footage where the footage couldn't be found. The flaws in the images are also rooted in their own issues— nighttime whitening and night vision snowflake spots I have disassembled them separately and have not been included in this post.

Step 1: Three blunders on the playback side, accounting for more than half

don't touch the camera yet; clean up the phone side. Three blunders are arranged by frequency:

first is the App player's built-in mute button, . The Mijia app's live screen is muted by default. There's a speaker icon on the interface, with a slash bar pressing it. You need to tap it to turn it on. The playback interface also has a separate switch—back then, the live screen was on, and the speaker in the playback screen was still pressed with a slash. I stared at the replay for a long time to find fault. The Ezviz Cloud Video App follows the same principle: the preview and playback interfaces each have their own functions.

second is of mobile media volume. The ringtone volume on the phone's side button doesn't count; hold down the volume button to see if the pop-up bar says "Media" or "Ringtone," or just play a video to try. Those who set up surveillance cameras for their parents pay special attention to this. Eight or nine times out of ten, the elderly have zero media volume on their phones, yet they firmly believe they haven't touched it.

third, the phone is either enabled with Do Not Disturb or Bluetooth still connected to the pair of earphones in the car. The sound was actually played, but it was just on another device. There is a feature in this situation: you can't even hear WeChat voice messages. One measurement reveals the truth.

Step 2: Record switch, hidden in device settings

the playback is cleared and there's still no sound, it depends on whether the machine records it. Each store has its own path, so I flipped through the three channels at home:

here's a detail to remind us: the high-end configuration at Ezviz Studio requires entering the device verification code the first time you enter—just the six capital letters on the phone label, stuck together with the WiFi password. Don't throw it into the box. Some older Ezviz models can only change audio parameters within the local network. The option under mobile data is grayed, so connect to WiFi at home and click again.

to determine if the recording switch is the root cause, there's a strict rule: the live screen has sound and playback is not, it's 90% likely because the recording wasn't turned on during the recording period. Only after this switch is turned on does the recording have sound. The previously recorded playback can't be restored, and the audio wasn't written into the file at the time, so even a god couldn't dub the old footage. Therefore, for machines with door locks and doorways in critical locations, you should check the switch on the day you install it, so you don't just stand there waiting to use it.

Step 3: Recorded but not right—muddy voice means distance, intercom mute means permission

switch fully on, speaker fully on, the sound is still quiet and muffled. This isn't a settings issue, it's a physical issue. Microphone pickup is quite far-fetched, and the manufacturer's trademark says it's very honest: the Xiaomi C400 gimbal phone is rated for a pickup range of around 5 meters, while the 3K model is rated for up to 8 meters. Beyond this distance, the voices become a blurred buzz, unrelated to the signal, purely because the microphone can't reach.

The one in my yard has suffered this kind of loss." The machine hung under the eaves, and people stood in the middle of the yard talking, barely audible in the replay; When they reached the courtyard gate, after seven or eight meters, only the sound of the wind remained. It's not that the machine is broken; it's just that it has such strong ears. If you want to hear voices clearly at the courtyard gate, you either move the device closer or add a separate head at the entrance. I wrote in my about how to distinguish points in the home monitoring network planning article, saying that sound and images require distance.

there's another hidden issue: the microphone jack is blocked. There is a small pinhole-sized hole on the side or bottom of the camera body—that's the microphone. Some installers installed machines close to the corner, while others put dust covers on the hole. Its behavior is quite distinctive—you can hear shouts nearby, but if you deviate from the angle even slightly, it gets stifled. On the day of assembly, I ran my finger around the machine to confirm the small hole was exposed—it took half a minute.

then there's intercom (when you hold the app while the speaker plays the sound on the camera), this is the fourth thing, and it doesn't share the same inspection as video recording. It adds an extra step: your phone needs to capture the sound first. In your phone's system settings, find the app and check if microphone permission is granted. After Android 9, machine permissions are strictly controlled; new apps don't provide microphones by default, so you have to manually turn them on.

my old device that only lets the cat watch. When I first set up the network, I randomly clicked permissions. Later, when I tried to call the cat over through the camera, I held down and spoke without any response. After checking for a long time, it turned out the phone's microphone wasn't granted. The characteristic of this problem is easy to recognize: you can hear what's happening on the other side of the camera, but you can't hear it over there. If Mi Home devices simply show 'offline and cannot connect,' that's another troubleshooting option. Mi Home devices always show offline I wrote a separate article about it, just check the symptoms.

Also, don't bring your phone too close to the camera during intercom. The camera speaker lets you speak, then gets caught in by its own microphone, and when amplified in cycle, it's a piercing howl—just like a KTV microphone clashing with speakers. After two or three meters, it quieted down.

recording matter, it's better to pretend to think it through before than to dwell on it afterward

to be honest in the end. Just because you can record sound doesn't mean you have to record everything. If the unit at the door faces the hallway or the neighbor's door, the recording isn't just about your own family—it's fine to keep it for yourself, but if a dispute arises and you want to use the recording as evidence or post it in the owners' group, you have to carefully consider whether there are other people's conversations inside. I turned off the recording on the one at my doorstep, leaving only the footage: voiceprint at the door is useless, just see the face clearly. In the yard and living room, these two units were running for recording, useful for watching cats and listening to noise.

There's no standard answer to this trade-off, but thinking it over before installing is better than struggling after recording. I wrote more thoroughly about the security of the camera's own account passwords and firmware in the the camera was peeked on, so I read it accordingly.

Finishing: A table is passed in order

after five steps and still no sound, consider the machine itself—try logging into the same account with another phone. If the phone makes noise, that's the phone's problem. If the phone doesn't make noise and the firmware is updated, then the microphone is faulty—contact after-sales service. That time my cat grabbed the cup, it ended up stuck at steps 1 and 3: the playback speaker wasn't turned on, and the recording switch wasn't even on during the earliest setup. The last few days all the recordings were dud. After flipping the switch, even the muffled sound of the cat landing was clearly recorded.