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avformat/movenc: split MPEG-4 bit rate value calculation

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This can now be re-utilized in other places.
This commit is contained in:
Jan Ekström 2020-09-20 14:41:18 +03:00
parent e71d73b096
commit 667d5045d3
1 changed files with 34 additions and 10 deletions
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44
libavformat/movenc.c
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@ -633,12 +633,41 @@ static unsigned compute_avg_bitrate(MOVTrack *track)
return size * 8 * track->timescale / track->track_duration;
}
struct mpeg4_bit_rate_values {
uint32_t buffer_size; ///< Size of the decoding buffer for the elementary stream in bytes.
uint32_t max_bit_rate; ///< Maximum rate in bits/second over any window of one second.
uint32_t avg_bit_rate; ///< Average rate in bits/second over the entire presentation.
};
static struct mpeg4_bit_rate_values calculate_mpeg4_bit_rates(MOVTrack *track)
{
AVCPBProperties *props =
(AVCPBProperties*)av_stream_get_side_data(track->st,
AV_PKT_DATA_CPB_PROPERTIES,
NULL);
struct mpeg4_bit_rate_values bit_rates = { 0 };
bit_rates.avg_bit_rate = compute_avg_bitrate(track);
// (FIXME should be max rate in any 1 sec window)
bit_rates.max_bit_rate = FFMAX(track->par->bit_rate,
bit_rates.avg_bit_rate);
// utilize values from properties if we have them available
if (props) {
bit_rates.max_bit_rate = FFMAX(bit_rates.max_bit_rate,
props->max_bitrate);
bit_rates.buffer_size = props->buffer_size / 8;
}
return bit_rates;
}
static int mov_write_esds_tag(AVIOContext *pb, MOVTrack *track) // Basic
{
AVCPBProperties *props;
struct mpeg4_bit_rate_values bit_rates = calculate_mpeg4_bit_rates(track);
int64_t pos = avio_tell(pb);
int decoder_specific_info_len = track->vos_len ? 5 + track->vos_len : 0;
unsigned avg_bitrate;
avio_wb32(pb, 0); // size
ffio_wfourcc(pb, "esds");
@ -669,14 +698,9 @@ static int mov_write_esds_tag(AVIOContext *pb, MOVTrack *track) // Basic
else
avio_w8(pb, 0x11); // flags (= Visualstream)
props = (AVCPBProperties*)av_stream_get_side_data(track->st, AV_PKT_DATA_CPB_PROPERTIES,
NULL);
avio_wb24(pb, props ? props->buffer_size / 8 : 0); // Buffersize DB
avg_bitrate = compute_avg_bitrate(track);
avio_wb32(pb, props ? FFMAX3(props->max_bitrate, props->avg_bitrate, avg_bitrate) : FFMAX(track->par->bit_rate, avg_bitrate)); // maxbitrate (FIXME should be max rate in any 1 sec window)
avio_wb32(pb, avg_bitrate);
avio_wb24(pb, bit_rates.buffer_size); // Buffersize DB
avio_wb32(pb, bit_rates.max_bit_rate); // maxbitrate
avio_wb32(pb, bit_rates.avg_bit_rate);
if (track->vos_len) {
// DecoderSpecific info descriptor