[FFmpeg-user] Identifying an MP4 file

[Henk D. Schoneveld]

On 31 Mar 2016, at 15:22, Sreenath BH <bhsreenath at gmail.com> wrote:

> Hi All,
> 
> We have a HTTP Live Streaming (HLS) setup where we transcode incoming
> video files to H264 video and AAC audio and build playlist files from
> that. We want to avoid this step if the input file is already a MP4
> file.
> 
> I know that MP4 is just a container and does not imply H264 and AAC.
> 
> I am planning to check the audio and video codec IDs in our program
> after getting the stream information using avformat_find_stream_info.
> 
> So, if the video codec ID and Audio codec ID are respectively,
> 
> AV_CODEC_ID_H264 and AV_CODEC_ID_AAC
> 
> Is it sufficient to qualify it as a MP4 file?
> 
> The reason I ask is that there are some flv files that use the same
> codecs, but I am not sure if it would be safe it to treat it on par
> with an "authentic" mp4 file.
> 
> Are there any things that I need to check before concluding that the
> video is fit for HLS streaming?
There are also MPEG2TS containers with h264 but often with other audio-codecs, used in television broadcast. Further there are interlaced and progressive versions and the resolution/bitrate, high bitrates, could be a problem for the players your audience uses.
> 
> thanks,
> Sreenath
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