[FFmpeg-devel] [PATCH v2 1/3] avformat/mpegtsenc: use total_size instead of avio_tell()

[Marton Balint]

On Thu, 22 Oct 2020, lance.lmwang at gmail.com wrote:

> From: Limin Wang <lance.lmwang at gmail.com>
>
> avio_tell() fails to get the amount of data written so far when the
> underlying IO context is flushed to segments.
>
> Please test with below command:
> $ ./ffmpeg  -f lavfi -i testsrc=duration=100:size=vga -c:v libx264 -x264opts \
>  nal-hrd=cbr:force-cfr=1 -b:v 500k -minrate 500k -maxrate 500k -bufsize 500k \
>  -f hls -hls_time 10  -hls_ts_options "muxrate=2000000" test%d.ts
>
> $ du -h test*.ts
> Before:
> 2.4M    test00.ts
> 4.8M    test11.ts
> 7.2M    test22.ts
> 9.6M    test33.ts
> 12M     test44.ts
> 15M     test55.ts
> 17M     test66.ts
> 20M     test77.ts
> 22M     test88.ts
> 24M     test99.ts
>
> After apply the patch:
> 2.4M   test00.ts
> 2.4M   test11.ts
> 2.4M   test22.ts
> 2.4M   test33.ts
> 2.4M   test44.ts
> 2.4M   test55.ts
> 2.4M   test66.ts
> 2.4M   test77.ts
> 2.4M   test88.ts
> 2.4M   test99.ts
>
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
> libavformat/mpegtsenc.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> index afdadda..5c97d63 100644
> --- a/libavformat/mpegtsenc.c
> +++ b/libavformat/mpegtsenc.c
> @@ -84,6 +84,7 @@ typedef struct MpegTSWrite {
>     int64_t next_pcr;
>     int mux_rate; ///< set to 1 when VBR
>     int pes_payload_size;
> +    int64_t total_size;
>
>     int transport_stream_id;
>     int original_network_id;
> @@ -830,9 +831,9 @@ invalid:
>     return 0;
> }
> 
> -static int64_t get_pcr(const MpegTSWrite *ts, AVIOContext *pb)
> +static int64_t get_pcr(const MpegTSWrite *ts)
> {
> -    return av_rescale(avio_tell(pb) + 11, 8 * PCR_TIME_BASE, ts->mux_rate) +
> +    return av_rescale(ts->total_size + 11, 8 * PCR_TIME_BASE, ts->mux_rate) +
>            ts->first_pcr;
> }
> 
> @@ -840,13 +841,14 @@ static void write_packet(AVFormatContext *s, const uint8_t *packet)
> {
>     MpegTSWrite *ts = s->priv_data;
>     if (ts->m2ts_mode) {
> -        int64_t pcr = get_pcr(s->priv_data, s->pb);
> +        int64_t pcr = get_pcr(s->priv_data);
>         uint32_t tp_extra_header = pcr % 0x3fffffff;
>         tp_extra_header = AV_RB32(&tp_extra_header);
>         avio_write(s->pb, (unsigned char *) &tp_extra_header,
>                    sizeof(tp_extra_header));
>     }
>     avio_write(s->pb, packet, TS_PACKET_SIZE);
> +    ts->total_size += TS_PACKET_SIZE;
> }
> 
> static void section_write_packet(MpegTSSection *s, const uint8_t *packet)
> @@ -1228,7 +1230,7 @@ static void mpegts_insert_pcr_only(AVFormatContext *s, AVStream *st)
>     }
>
>     /* PCR coded into 6 bytes */
> -    q += write_pcr_bits(q, get_pcr(ts, s->pb));
> +    q += write_pcr_bits(q, get_pcr(ts));
>
>     /* stuffing bytes */
>     memset(q, 0xFF, TS_PACKET_SIZE - (q - buf));
> @@ -1315,7 +1317,7 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
>     while (payload_size > 0) {
>         int64_t pcr = AV_NOPTS_VALUE;
>         if (ts->mux_rate > 1)
> -            pcr = get_pcr(ts, s->pb);
> +            pcr = get_pcr(ts);
>         else if (dts != AV_NOPTS_VALUE)
>             pcr = (dts - delay) * 300;
> 
> @@ -1326,7 +1328,7 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
>         write_pcr = 0;
>         if (ts->mux_rate > 1) {
>             /* Send PCR packets for all PCR streams if needed */
> -            pcr = get_pcr(ts, s->pb);
> +            pcr = get_pcr(ts);
>             if (pcr >= ts->next_pcr) {
>                 int64_t next_pcr = INT64_MAX;
>                 for (int i = 0; i < s->nb_streams; i++) {
> @@ -1340,7 +1342,7 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
>                             ts_st2->last_pcr = FFMAX(pcr - ts_st2->pcr_period, ts_st2->last_pcr + ts_st2->pcr_period);
>                             if (st2 != st) {
>                                 mpegts_insert_pcr_only(s, st2);
> -                                pcr = get_pcr(ts, s->pb);
> +                                pcr = get_pcr(ts);
>                             } else {
>                                 write_pcr = 1;
>                             }

LGTM, thanks.

Marton