Re: [FFmpeg-devel] [PATCH] avformat/hlsenc: calculate bitrate for segments with duration < 0.5

[Steven Liu <lingjiujianke@gmail.com>]

Jack Lau via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> 于2025年3月24日周一 07:13写道：
>
> The previous code sets the bitrate to be calculated only when duration>0.5, which is obviously not general enough.
>
> In some scenarios, we may need to set hls_time<0.5, then the generated segments are all <0.5. At this time, because the bitrate is not calculated, max_bitrate is empty, and ff_hls_write_stream_info cannot write stream info normally, causing master_pl to be unavailable.
>
> Signed-off-by: Jack Lau <jacklau1222@qq.com>
> ---
>  libavformat/hlsenc.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
> index c6ffdb99e5..223c516103 100644
> --- a/libavformat/hlsenc.c
> +++ b/libavformat/hlsenc.c
> @@ -1150,9 +1150,7 @@ static int hls_append_segment(struct AVFormatContext *s, HLSContext *hls,
>
>      vs->total_size += size;
>      vs->total_duration += duration;
> -    if (duration > 0.5) {
> -        // Don't include the final, possibly very short segment in the
> -        // calculation of the max bitrate.
> +    if (duration > 0) {

I'm not sure if this will work well in llhls mode,
but when the network conditions are even slightly poor,
severe stuttering or even an inability to continue playback occurs.
This is because the segments are so small that the network overhead
exceeds the time it takes to play them.

>          int cur_bitrate = (int)(8 * size / duration);
>          if (cur_bitrate > vs->max_bitrate)
>              vs->max_bitrate = cur_bitrate;
> --
> 2.47.1
>
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Thanks
Steven
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