What Happens to Subtitles After CineX Converts a Video: Text, ASS and PGS

Subtitles do not all get the same treatment when CineX converts a video. Text-based tracks such as SRT and ASS are carried into the resulting MP4 as embedded subtitles. ASS styling such as positioning and color is reduced to plain text, while image-based subtitles such as PGS, VobSub and DVD subtitles are not preserved at all. In the current version, those image subtitle tracks are skipped without a warning.

This article is only about subtitles already inside the video file. CineX does not import an external subtitle file, create subtitles, translate them, or export a separate subtitle file afterward. If subtitles are essential to the way you watch a video, especially if you rely on PGS or on ASS layout, it is worth checking the subtitle type before you convert.

1. After conversion, subtitles have two very different outcomes

The useful distinction is not whether the video file is called MKV, MP4, AVI or TS. What matters here is whether the subtitle track contains text or images. Text can be converted into a subtitle form that fits inside the resulting MP4. Image subtitles cannot be carried over in the same way, so they have a different outcome.

CineX keeps the content of text subtitles, simplifies ASS styling, and does not preserve image-based subtitle tracks. Image subtitles are currently skipped without a notice.

Subtitle handling is one part of a conversion. It does not by itself tell you whether the video stream will be left as-is or fully converted. That separate decision is explained in how CineX decides which conversion path to use.

2. Text subtitles stay with the video as embedded MP4 subtitles

SRT and ASS are text-based subtitle formats. Their core data is written text tied to timing information. SSA, WebVTT and other text formats have no device sample behind them yet, so this page does not present them as verified. When those tracks are already inside the source video, CineX converts them into embedded subtitles that can live inside the output MP4.

“Preserved” does not mean the original subtitle format is copied over byte for byte. It means the subtitle content remains available inside the converted video. CineX does not also create a separate SRT, ASS or other subtitle file alongside the MP4.

This is why an MKV that contains subtitles should not be expected to produce an MP4 whose subtitle tracks are identical in every detail. The container changes, so the subtitle representation has to fit the destination as well. If your separate question is whether the video picture itself needs to be recompressed during MKV-to-MP4 conversion, see when CineX can convert MKV to MP4 without recompressing the video.

3. ASS keeps the words, not the original layout

ASS is the text format most likely to surprise people because it can carry much more than dialogue and timing. An ASS track may also use positioning, colors and other layout choices. CineX keeps the subtitle text, but those presentation details do not survive the conversion. The result is plain text.

For ordinary dialogue, that may still deliver the information you need. The difference becomes much more visible when layout is part of the meaning: lyrics placed in a particular region of the frame, different colors used for different speakers, or bilingual subtitles arranged in separate positions.

With ASS, the important boundary is simple: the words remain, while positioning, color and related layout styling do not.

If you mainly need readable dialogue, that tradeoff may be acceptable. If the layout itself carries meaning, checking the ASS track before conversion is one of the most important subtitle checks you can make.

4. PGS, VobSub and DVD subtitles are not preserved, and there is no warning yet

PGS, VobSub and DVD subtitles are fundamentally different from SRT or ASS. They are image-based subtitle tracks: what appears on screen is stored as subtitle graphics rather than ordinary text that can simply be rewritten into an MP4 text subtitle track.

Because MP4 embedded subtitles cannot carry those subtitle images in the form CineX produces, CineX does not preserve these tracks. More importantly, the current version does not show an alert before conversion or tell you afterward that an image subtitle track was omitted. It is skipped silently.

If a video depends on PGS, VobSub or DVD image subtitles, those subtitles will be missing from the converted file, and the current version will not notify you that they were skipped.

That behavior is a known defect, not a convenience feature. A video can finish converting successfully while still losing the subtitle track you actually needed. If subtitles are non-negotiable for a particular movie or episode, the subtitle type deserves the same attention as the picture and audio.

5. External subtitle files cannot be added during conversion

If you have a video file plus a separate SRT or ASS file, CineX cannot import that external subtitle file and merge it into the video during conversion. CineX only processes subtitle tracks that are already embedded in the source video.

That makes one wording distinction important: CineX can process SRT or ASS when that subtitle is inside the video file. It does not mean CineX offers an “add subtitle file” step where you can browse for an external SRT and attach it to the conversion.

The reverse workflow is also outside the scope of the app. After conversion, CineX does not extract an embedded subtitle track into a standalone subtitle file. Its job is to convert the video into an MP4 that is easier to open directly on iPhone, iPad and Mac, not to act as a subtitle import, extraction or management tool.

6. Multiple subtitle tracks are processed one by one, but the Simplified/Traditional distinction is lost

A video can contain more than one subtitle track, and CineX processes those tracks individually rather than stopping after the first one. For example, if a file contains 3 text subtitle tracks, each is handled in turn. If the track list mixes text and image subtitles, the text tracks follow the text-subtitle rules while image-based tracks still are not preserved.

Chinese subtitles have one additional limitation: the Simplified-versus-Traditional distinction is lost during conversion. The subtitle text remains subject to the normal text-subtitle handling, but the converted file no longer distinguishes Simplified from Traditional Chinese. That may not matter if you only read the subtitle itself, but it matters if you need those two Chinese variants to remain clearly differentiated after conversion.

7. Why “subtitles are preserved” is too vague to be useful

Calling all of these tracks “subtitles” is convenient, but it hides the exact difference that determines the result. Text subtitles contain words and timing. Image subtitles contain pictures. CineX can convert the former into MP4 embedded subtitles, but it cannot place the latter into that same kind of subtitle track.

ASS sits in the middle. It is still text-based, so the words can remain, but some of the richer layout information has nowhere to go in the resulting subtitle form. The conversion therefore keeps the essential text while dropping positioning and color styling.

The practical takeaway is that the presence of a subtitle track is not enough information on its own. If subtitles are only a reading aid, text-track handling may be all you need. If the subtitle graphics or layout are part of the presentation, you should treat that as a conversion boundary rather than assume “subtitle support” covers it.

8. Limits: what this workflow cannot do

• If you rely on PGS, VobSub or DVD image subtitles, those tracks will not be preserved, and the current version will not warn you.
• If you want to add an external SRT, ASS or other subtitle file during conversion, CineX does not support that import workflow.
• If you depend on ASS positioning or color to understand lyrics, speakers or bilingual layout, those styling details will become plain text.
• If you need a separate subtitle file after conversion, CineX does not export one.
• If you need Simplified and Traditional Chinese subtitles to remain explicitly distinguished after conversion, that distinction is not retained.

Common questions

Will my subtitles still be there after I convert the video?

It depends on the subtitle type. SRT and ASS text subtitles are converted into embedded MP4 subtitles. ASS styling is simplified. PGS, VobSub and DVD image subtitles are not preserved.

My subtitles are PGS. What happens after conversion?

They are not preserved. PGS is an image-based subtitle type, and the current version also does not warn you that the track was skipped. That silent skip is a known defect.

Will ASS colors and positioning survive?

No. The text content remains, but positioning, color and related ASS layout styling are reduced to plain text. If the layout carries meaning, the converted result can look substantially different.

Can I choose my own SRT file and add it?

No. CineX does not import external subtitle files. It only processes subtitle tracks already embedded in the source video.

If a video has several subtitle tracks, does CineX keep only one?

No. CineX processes subtitle tracks one by one. Text tracks follow the text-subtitle rules; any image-based subtitle tracks among them still are not preserved.

Axiom One LLC — CineX. Figures current as of 24 September 2026.