Subtitle The Order

Captions and subtitles are a lot more complex than most people realize. While they may seem interchangeable, understanding the differences between captions and subtitles is an important step in determining the most appropriate option for your video content.

subtitle The Order

In the accessibility space, timed text files are usually intended to pair the transcription of dialogue and/or sound to media. The timing information allows the text to be synchronized to specific time codes of media. Both captions and subtitles are forms of timed text.

Subtitles can appear in a variety of styles, but often appear as white or yellow text outlined in black, or with a black dropshadow. It is also common for subtitles to mimic the appearance of captions. Placement varies, but is often centered at the bottom of the screen for readability and ease in translation. When graphics or text appear in the lower third of the video, subtitles are typically placed just above the graphic/text. Subtitles can sometimes be customized by viewers, depending on where media is being viewed.

Forced narrative (FN) subtitles, also known as forced subtitles, clarify pertinent information meant to be understood by the viewer. FN subtitles are overlaid text used to clarify dialogue, burned-in texted graphics, and other information that is not otherwise explained or easily understood by the viewer.

I am trying to set the position and formatting of title, subtitle in the slide. I tried to change the position, font type of title and subtitle present in all slides using the following code. It works on title but there are no changes for subtitle position, font type. How can we get reference of subtitle to work on its position, font size etc.

The order of your -map options determines the order of the streams in the output. In this example the input file has audio as stream #0 and video as stream #1 (which is possible but unusual). Example to re-position video so it is listed first, followed by the audio:

Each input or output url can, in principle, contain any number of streams ofdifferent types (video/audio/subtitle/attachment/data). The allowed number and/ortypes of streams may be limited by the container format. Selecting whichstreams from which inputs will go into which output is either done automaticallyor with the -map option (see the Stream selection chapter).

As a general rule, options are applied to the next specifiedfile. Therefore, order is important, and you can have the sameoption on the command line multiple times. Each occurrence isthen applied to the next input or output file.Exceptions from this rule are the global options (e.g. verbosity level),which should be specified first.

ffmpeg provides the -map option for manual control of stream selection in eachoutput file. Users can skip -map and let ffmpeg perform automatic stream selection asdescribed below. The -vn / -an / -sn / -dn options can be used to skip inclusion ofvideo, audio, subtitle and data streams respectively, whether manually mapped or automaticallyselected, except for those streams which are outputs of complex filtergraphs.

In the absence of any map options for a particular output file, ffmpeg inspects the outputformat to check which type of streams can be included in it, viz. video, audio and/orsubtitles. For each acceptable stream type, ffmpeg will pick one stream, when available,from among all the inputs.

Stream handling is independent of stream selection, with an exception for subtitles describedbelow. Stream handling is set via the -codec option addressed to streams within aspecific output file. In particular, codec options are applied by ffmpeg after thestream selection process and thus do not influence the latter. If no -codec option isspecified for a stream type, ffmpeg will select the default encoder registered by the outputfile muxer.

An exception exists for subtitles. If a subtitle encoder is specified for an output file, thefirst subtitle stream found of any type, text or image, will be included. ffmpeg does not validateif the specified encoder can convert the selected stream or if the converted stream is acceptablewithin the output format. This applies generally as well: when the user sets an encoder manually,the stream selection process cannot check if the encoded stream can be muxed into the output file.If it cannot, ffmpeg will abort and all output files will fail to be processed.

The 2nd output file, out2.srt, only accepts text-based subtitle streams. So, even thoughthe first subtitle stream available belongs to C.mkv, it is image-based and hence skipped.The selected stream, stream 2 in B.mp4, is the first text-based subtitle stream.

The aresample filter is sent the first unused audio stream, that of A.avi. Since this filteroutput is also unlabelled, it too is mapped to the first output file. The presence of -anonly suppresses automatic or manual stream selection of audio streams, not outputs sent fromfiltergraphs. Both these mapped streams shall be ordered before the mapped stream in out1.mp4.

Matches the stream with this index. E.g. -threads:1 4 would set thethread count for the second stream to 4. If stream_index is used as anadditional stream specifier (see below), then it selects stream numberstream_index from the matching streams. Stream numbering is based on theorder of the streams as detected by libavformat except when a program ID isalso specified. In this case it is based on the ordering of the streams in theprogram.

Add an attachment to the output file. This is supported by a few formatslike Matroska for e.g. fonts used in rendering subtitles. Attachmentsare implemented as a specific type of stream, so this option will adda new stream to the file. It is then possible to use per-stream optionson this stream in the usual way. Attachment streams created with thisoption will be created after all the other streams (i.e. those createdwith -map or automatic mappings).

This lowers the latency of subtitles for which the end packet or the followingsubtitle has not yet been received. As a drawback, this will most likely leadto duplication of subtitle events in order to cover the full duration, sowhen dealing with use cases where latency of when the subtitle event is passedon to output is not relevant this option should not be utilized.

Requires -fix_sub_duration to be set for the relevant input subtitlestream for this to have any effect, as well as for the input subtitle streamhaving to be directly mapped to the same output in which the heartbeat streamresides.

Fix subtitles durations. For each subtitle, wait for the next packet in thesame stream and adjust the duration of the first to avoid overlap. This isnecessary with some subtitles codecs, especially DVB subtitles, because theduration in the original packet is only a rough estimate and the end isactually marked by an empty subtitle frame. Failing to use this option whennecessary can result in exaggerated durations or muxing failures due tonon-monotonic timestamps.

This option may be specified multiple times, each adding more streams to theoutput file. Any given input stream may also be mapped any number of times as asource for different output streams, e.g. in order to use different encodingoptions and/or filters. The streams are created in the output in the same orderin which the -map options are given on the commandline.

As a special exception, you can use a bitmap subtitle stream as input: itwill be converted into a video with the same size as the largest video inthe file, or 720x576 if no video is present. Note that this is anexperimental and temporary solution. It will be removed once libavfilter hasproper support for subtitles.

When stats for multiple streams are written into a single file, the linescorresponding to different streams will be interleaved. The precise order ofthis interleaving is not specified and not guaranteed to remain stable betweendifferent invocations of the program, even with the same options.

First ffmpeg searches for a file named arg.ffpreset in thedirectories $FFMPEG_DATADIR (if set), and $HOME/.ffmpeg, and inthe datadir defined at configuration time (usually PREFIX/share/ffmpeg)or in a ffpresets folder along the executable on win32,in that order. For example, if the argument is libvpx-1080p, it willsearch for the file libvpx-1080p.ffpreset.

When the pre option is specified, ffmpeg will look for files with thesuffix .avpreset in the directories $AVCONV_DATADIR (if set), and$HOME/.avconv, and in the datadir defined at configuration time (usuallyPREFIX/share/ffmpeg), in that order.

Knowing how to synchronize each word sequence with the speech is perhaps the greatest difficulty. Inspired by the workflow of professional subtitlers, here is a method to achieve it efficiently:

Although often outsourced to machine translations or to professionals services, subtitle translation is an art that requires a great deal of rigor. Here is what you need to remember when translating into any language and for any nationality:

Often neglected, positioning, size, color, font and layout are not useless details. On the contrary, they largely define the legibility and clarity of your subtitles. To choose the right settings, here are some important tips:

When you have made your subtitle file, you may wonder how to add your subtitles to your video. Many platforms give you the opportunity to add your subtitle file as a closed caption (CC) afterwards. But there is also the possibility to burn subtitles with specific parameters into your video. It all depends on your objective:

However, in recent years, some fascinating automatic subtitling software has emerged on the market. With technologies such as enhanced speech recognition and translation engine, an ergonomic subtitle editor, and collaborative tools, they save you an enormous amount of time on your video production. Their unique features guarantee you a superior result compared to default solutions like YouTube.

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