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demux_lavf: select initial edition only by the program's variant_bitrate

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The per-stream variant_bitrate is not a reliable selection key. FFmpeg
attributes the whole variant's bandwidth to individual streams, and for
streams shared by multiple variants the value was bogus or missing
depending on the number of variants sharing the stream. The program
metadata always carries the exact HLS variant BANDWIDTH, so use it as
the only key and drop the per-stream fallback.

Note that with `--flatten-editions` tracks are selected by their own
tags, so they may still use bogus values.

For context, there is currently a bug in lavf where, depending on the
number of variants sharing a stream, the stream may or may not get
`variant_bitrate`. This will be fixed in a future FFmpeg release.
This commit is contained in:
Kacper Michajłow committed 2026-08-17 19:57:13 +02:00
1 parent b6d3434493
commit e7191f2a65
1 file changed
+10 -23
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demux/demux_lavf.c
+10 -23
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@@ -1038,6 +1038,7 @@ static void build_editions(demuxer_t *demuxer)
// lavf happened to discover them.
AVProgram **progs = talloc_memdup(NULL, avfc->programs, avfc->nb_programs * sizeof(progs[0]));
qsort(progs, avfc->nb_programs, sizeof(progs[0]), cmp_avprogram);
bool *nonempty = talloc_zero_array(progs, bool, avfc->nb_programs);
int first_nonempty = -1;
for (unsigned i = 0; i < avfc->nb_programs; i++) {
@@ -1092,6 +1093,7 @@ static void build_editions(demuxer_t *demuxer)
if (title)
mp_tags_set_str(ed.metadata, "title", title);
nonempty[i] = track_count > 0;
if (track_count > 0 && first_nonempty < 0)
first_nonempty = demuxer->num_editions;
@@ -1104,39 +1106,24 @@ static void build_editions(demuxer_t *demuxer)
if (edition_id >= 0 && edition_id < demuxer->num_editions)
selected = edition_id;
// Select initial edition by best variant bitrate. Prefer the program's
// video stream as the representative, falling back to audio for
// audio-only variants (e.g. HLS audio-only renditions).
// Select initial edition by best variant bitrate from the program's
// metadata (HLS variant BANDWIDTH).
if (selected < 0 && hls_bitrate >= 0) {
int best = -1;
int best_bitrate = 0;
bool best_ok = false;
for (int n = 0; n < demuxer->num_editions; n++) {
AVProgram *prog = progs[n];
struct sh_stream *rep = NULL;
for (unsigned j = 0; j < prog->nb_stream_indexes; j++) {
unsigned idx = prog->stream_index[j];
if (idx >= priv->num_streams || !priv->streams[idx]->sh)
continue;
struct sh_stream *sh = priv->streams[idx]->sh;
if (sh->hls_bitrate <= 0)
continue;
if (sh->type == STREAM_VIDEO) {
rep = sh;
break;
}
if (sh->type == STREAM_AUDIO && !rep)
rep = sh;
}
if (!rep)
int bitrate = dict_get_decimal(prog->metadata, "variant_bitrate", 0);
if (bitrate <= 0 || !nonempty[n])
continue;
bool ok = rep->hls_bitrate <= hls_bitrate;
bool ok = bitrate <= hls_bitrate;
if (best < 0 || (ok && !best_ok) ||
(ok && best_ok && rep->hls_bitrate > best_bitrate) ||
(!ok && !best_ok && rep->hls_bitrate < best_bitrate))
(ok && best_ok && bitrate > best_bitrate) ||
(!ok && !best_ok && bitrate < best_bitrate))
{
best = n;
best_bitrate = rep->hls_bitrate;
best_bitrate = bitrate;
best_ok = ok;
}
}