Subtitles: How to Check SRT Quality After Local Transcription
The Subtitles tool recognizes speech from an uploaded audio file directly in the browser and creates an SRT file with timestamps. This is convenient for quickly preparing subtitles for video, but the quality of the result depends on the clarity of speech, background noise, terminology and accent. In this guide we will objectively evaluate the obtained SRT file. You will learn how to check text accuracy, completeness of speech transmission and correctness of timings, and also understand when the result can be used immediately and when it requires manual editing. We will consider specific examples and provide a check list for quick checking.
Open tool: Subtitle generator ↗What exactly does the tool create and what do you get on output
The tool accepts an audio file (up to 20 MB or 5 minutes of sound) and performs local transcription: the audio is not sent to external servers, recognition takes place in your browser. As output you get a text file in SRT format - the standard subtitle format, where each block contains a serial number, start and end timestamps and the text. It is important to understand that the tool does not perform automatic synchronization with video, does not break long replicas into short lines and does not add styles. It only creates timestamps based on pauses in speech and recognizes words.
Since transcription is local, quality depends on the recognition model which may make mistakes on specific terms, proper names, numbers and with strong accent. Moreover, the tool does not support batch processing, does not save history and has no settings to improve recognition. Therefore evaluating the result is your task. You should check how accurately the text was transmitted, whether all replicas got into the file and whether the time intervals are set correctly.
The output file can be downloaded or copied as plain text. This means you can open it in any text editor or load it into a subtitle program. But before use make sure the SRT format is observed: line numbers, timestamps in HH:MM:SS,ms format and empty lines between blocks. If the tool violated the structure for some reason, the file may not open in a player.
Example: you upload an audio file with a lecture recording. The tool returns an SRT file with 45 subtitles. You open it in Notepad and see that the timestamps go sequentially, but in one place a replica is missed.
Recognition accuracy: how to measure and what counts as an error
Accuracy is the percentage of words recognized correctly. To evaluate it, take an audio fragment lasting 1-2 minutes, listen to it and compare with the text in SRT. Pay attention to the following types of errors: substitutions (one word replaced by another, similar in sound), omissions (a word or phrase is missing), insertions (extra words, which were not in speech) and errors in numbers, names, abbreviations. Count the number of errors and divide by the total number of words in this fragment - you get an approximate accuracy. For everyday speech 90-95% is acceptable, for technical or medical - higher than 98%.
Pay special attention to terms and proper names. The tool does not have a built-in dictionary for your domain, so it may write "neural network" as "neural network" or "API" as "a pi". If the audio has numbers, check whether they are written correctly: "fifty" may turn into "50" or "5.0". This is critical for subtitles to educational materials or financial reports.
If accuracy is lower than desired, do not try to fix all errors manually - this may take more time than re-recording. Instead evaluate how much the errors distort the meaning. If they are rare and do not hinder understanding, subtitles can be used as a draft. If the errors change the meaning of phrases, it is better to re-record the audio with better quality or use another tool.
Example: in the audio it is said "We use API for integration". In SRT it may be "We use a pi for integration". This is an error, but it does not distort the meaning if the viewer is familiar with the term.
Completeness: whether all replicas got into subtitles
Completeness is the absence of missing speech fragments. The tool may skip words or entire sentences if speech is fast, indistinct or overlapped by noise. To check completeness, select several audio segments where the speaker makes pauses and compare the number of replicas in SRT with what you hear. If the audio has 10 sentences and SRT has only 8, then two were missed. Omissions are especially dangerous in subtitles for movies or interviews, where every phrase is important.
Also check whether the tool combined several short replicas into one long one. This may lead to a subtitle hanging on the screen too long or not matching the speech moment. In SRT each block must correspond to one replica or a logically completed fragment. If the tool created one block for 30 seconds, it is inconvenient for reading.
If you find omissions, you can add them manually, but it is laborious. Better evaluate how critical they are. In entertainment content small omissions are acceptable, in educational or legal - no. Remember that the tool does not guarantee 100% completeness, especially on recordings with poor sound quality.
Example: in the audio the speaker says "Today we will consider three topics: first, second and third". In SRT it may be only "Today we will consider three topics: first and second". The third topic is gone.
Timings: synchronization with speech and readability
Timestamps in SRT determine when a subtitle appears and disappears. The tool automatically sets them based on pauses in speech, but not always accurately. Check whether the appearance of a subtitle matches the start of the phrase. If a subtitle appears 1-2 seconds earlier or later, it may confuse the viewer. Especially important for fast dialogues. Also make sure the display duration of a subtitle is sufficient for reading: on average a reader reads 15-20 characters per second. If a subtitle contains 100 characters and is shown for 2 seconds, it is impossible to read.
The tool may create too short or too long intervals. For example, if the speaker makes a pause inside a sentence, the tool may split one phrase into two subtitles with unnatural boundaries. This is not a format error, but reduces convenience. You can manually adjust timings in a subtitle editor, but it takes time.
Also check whether there are overlapping subtitles (when one block ends later than the next one starts). In SRT this is not allowed, as the player may display them simultaneously or ignore them. If the tool made such a mistake, the file needs to be fixed.
Example: subtitle "Hello, today we will talk about" appears at 00:00:05,000 and disappears at 00:00:05,800. This is 0.8 seconds for 30 characters - too fast. Better expand the interval to 2 seconds.
Practical example of assessment: step-by-step review
Suppose you uploaded an audio file with an interview recording lasting 3 minutes. The tool returned an SRT file with 25 subtitles. Your task is to evaluate its quality. Start with a visual inspection: open the file in a text editor. Check that each block has a number, timestamps and text, and that there are empty lines between blocks. If the structure is broken, the file may not work.
Then select the first 30 seconds of audio and listen to them, comparing with the text. Count errors: for example, out of 50 words 3 were recognized incorrectly. Accuracy - 94%. Check completeness: in audio 5 sentences, in SRT - 5. Good. Now check timings: the first subtitle should appear when the speaker starts the first phrase. If it lags by 1 second, it is acceptable, but if by 3 - bad.
Repeat this procedure for several random segments. If accuracy and completeness are stably high, and timings are close to speech, subtitles can be used. If not - determine which errors are critical. For example, if names or numbers are mixed up, this may be seriously. In such case manual editing or re-transcription with cleaner audio is required.
Example: you check a fragment 00:01:20-00:01:50. In audio: "Project starts in May and will end in September". In SRT: "Project starts in May and will end in September". All correct. Timing: subtitle appears at 00:01:22,000, although speech starts at 00:01:21,500. Delay 0.5 seconds - acceptable.
Tool limitations and what it cannot do
The tool does not perform noise reduction, does not separate voices, does not recognize speech with strong accent as well as specialized services. It does not support video upload, only audio. Maximum audio length - 5 minutes or 20 MB, so long recordings have to be split into parts. No batch processing, so each file has to be uploaded separately. No possibility to edit subtitles within the tool - only download and edit in another editor.
Moreover, the tool does not guarantee that all words will be recognized correctly. The model may make mistakes on specific terms, abbreviations, numbers. It does not adapt to your dictionary. Therefore for professional use subtitles created by this tool require mandatory checking and editing. Do not rely on automatic evaluation - it simply does not exist.
Also remember that audio is processed locally, but this does not cancel the limitations on size and duration. If your file is larger than 20 MB, it needs to be compressed or trimmed. The tool is not intended for creating subtitles for movies with multiple speakers and overlaid music - in such cases quality will be low.
Example: you upload audio with a webinar recording lasting 10 minutes. The tool will not accept the file, as the 5 minute limit is exceeded. You have to split the recording into two parts and process separately.
Check list for quick quality assessment of subtitles
To not spend time on full analysis, use a short check list. First: check SRT structure - numbers, marks, empty lines. Second: select 1-2 minutes of audio and compare text. Evaluate accuracy (at least 90% for everyday speech) and completeness (all replicas are in place). Third: check timings - subtitles should appear on time and not overlap. Fourth: make sure the display duration is sufficient for reading (at least 1 second for 15-20 characters). Fifth: check for errors in names, numbers, terms critical for meaning.
If the result is satisfactory by all points, subtitles can be used. If there are critical errors, fix them manually or re-record the audio. Do not try to fix everything - focus on meaning errors. Remember that the tool is just an assistant, not a replacement for professional transcription.
To speed up checking you can use the search function in a text editor: search for frequently occurring terms and check their spelling. Also useful to listen to audio at 1.5x speed to quickly compare text. But do not neglect spot checking - it gives a picture of overall quality.
Example check list: 1) SRT structure - ok. 2) Accuracy on 1 min fragment - 92%. 3) Completeness - all replicas. 4) Timings - delay 0.5 s. 5) Errors in numbers - none. Conclusion: can be used after light editing.
Assessing the quality of subtitles created by the Subtitles tool requires careful analysis of accuracy, completeness and timings. Do not rely on automatic metrics - they are not there. Instead use spot checking and a check list. Remember that the tool works locally and has limitations on duration and file size. It is not intended for professional transcription without editing, but can be useful for quickly creating rough subtitles. Always check critical meaning fragments and be ready for manual correction. Following these recommendations will help you efficiently use the tool and get an acceptable result.
Open tool: Subtitle generator ↗Interface translations are machine-assisted and may need refinement.