[FFmpeg-devel] [PATCH 1/2] avformat/dv: allow returning damaged audio
Marton Balint
cus at passwd.hu
Sat Aug 1 20:28:53 EEST 2020
On Sat, 1 Aug 2020, Michael Niedermayer wrote:
> Fixes: Ticket8762
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
> libavformat/dv.c | 49 +++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 42 insertions(+), 7 deletions(-)
If "dv remux loses sync", then the timestamps should be fixed, not
additional packets should be generated based on previously read packet
data (which is a fragile approach to begin with, e.g. what if the first
frame is the corrupt one?).
Regards,
Marton
>
> diff --git a/libavformat/dv.c b/libavformat/dv.c
> index e99422d4b5..7ebe1815b3 100644
> --- a/libavformat/dv.c
> +++ b/libavformat/dv.c
> @@ -34,12 +34,18 @@
> #include "libavcodec/dv_profile.h"
> #include "libavcodec/dv.h"
> #include "libavutil/channel_layout.h"
> +#include "libavutil/opt.h"
> #include "libavutil/intreadwrite.h"
> #include "libavutil/mathematics.h"
> #include "libavutil/timecode.h"
> #include "dv.h"
> #include "libavutil/avassert.h"
>
> +enum AudioConceal {
> + AUDIO_CONCEAL_PASS = 1,
> + AUDIO_CONCEAL_DROP = 0,
> +};
> +
> struct DVDemuxContext {
> const AVDVProfile* sys; /* Current DV profile. E.g.: 525/60, 625/50 */
> AVFormatContext* fctx;
> @@ -50,6 +56,8 @@ struct DVDemuxContext {
> int ach;
> int frames;
> uint64_t abytes;
> + uint8_t as_pack[5];
> + int dvaudio_concealment;
> };
>
> static inline uint16_t dv_audio_12to16(uint16_t sample)
> @@ -72,7 +80,7 @@ static inline uint16_t dv_audio_12to16(uint16_t sample)
> return result;
> }
>
> -static const uint8_t *dv_extract_pack(const uint8_t *frame, enum dv_pack_type t)
> +static const uint8_t *dv_extract_pack(DVDemuxContext *d, const uint8_t *frame, enum dv_pack_type t)
> {
> int offs;
> int c;
> @@ -101,6 +109,13 @@ static const uint8_t *dv_extract_pack(const uint8_t *frame, enum dv_pack_type t)
> break;
> }
>
> + if (t == dv_audio_source || t == dv_audio_control) {
> + if (frame[offs] == t) {
> + memcpy(d->as_pack, &frame[offs], sizeof(d->as_pack));
> + } else if (d->as_pack[0] && d->dvaudio_concealment == AUDIO_CONCEAL_PASS)
> + return d->as_pack;
> + }
> +
> return frame[offs] == t ? &frame[offs] : NULL;
> }
>
> @@ -116,7 +131,7 @@ static const int dv_audio_frequency[3] = {
> * 3. Audio is always returned as 16-bit linear samples: 12-bit nonlinear samples
> * are converted into 16-bit linear ones.
> */
> -static int dv_extract_audio(const uint8_t *frame, uint8_t **ppcm,
> +static int dv_extract_audio(DVDemuxContext *c, const uint8_t *frame, uint8_t **ppcm,
> const AVDVProfile *sys)
> {
> int size, chan, i, j, d, of, smpls, freq, quant, half_ch;
> @@ -124,7 +139,7 @@ static int dv_extract_audio(const uint8_t *frame, uint8_t **ppcm,
> const uint8_t *as_pack;
> uint8_t *pcm, ipcm;
>
> - as_pack = dv_extract_pack(frame, dv_audio_source);
> + as_pack = dv_extract_pack(c, frame, dv_audio_source);
> if (!as_pack) /* No audio ? */
> return 0;
>
> @@ -224,7 +239,7 @@ static int dv_extract_audio_info(DVDemuxContext *c, const uint8_t *frame)
> const uint8_t *as_pack;
> int freq, stype, smpls, quant, i, ach;
>
> - as_pack = dv_extract_pack(frame, dv_audio_source);
> + as_pack = dv_extract_pack(c, frame, dv_audio_source);
> if (!as_pack || !c->sys) { /* No audio ? */
> c->ach = 0;
> return 0;
> @@ -292,7 +307,7 @@ static int dv_extract_video_info(DVDemuxContext *c, const uint8_t *frame)
> c->vst->avg_frame_rate = av_inv_q(c->vst->time_base);
>
> /* finding out SAR is a little bit messy */
> - vsc_pack = dv_extract_pack(frame, dv_video_control);
> + vsc_pack = dv_extract_pack(c, frame, dv_video_control);
> apt = frame[4] & 0x07;
> is16_9 = (vsc_pack && ((vsc_pack[2] & 0x07) == 0x02 ||
> (!apt && (vsc_pack[2] & 0x07) == 0x07)));
> @@ -312,7 +327,7 @@ static int dv_extract_timecode(DVDemuxContext* c, const uint8_t* frame, char *tc
> // is only relevant for NTSC systems.
> int prevent_df = c->sys->ltc_divisor == 25 || c->sys->ltc_divisor == 50;
>
> - tc_pack = dv_extract_pack(frame, dv_timecode);
> + tc_pack = dv_extract_pack(c, frame, dv_timecode);
> if (!tc_pack)
> return 0;
> av_timecode_make_smpte_tc_string(tc, AV_RB32(tc_pack + 1), prevent_df);
> @@ -384,7 +399,7 @@ int avpriv_dv_produce_packet(DVDemuxContext *c, AVPacket *pkt,
> ppcm[i] = c->audio_buf[i];
> }
> if (c->ach)
> - dv_extract_audio(buf, ppcm, c->sys);
> + dv_extract_audio(c, buf, ppcm, c->sys);
>
> /* We work with 720p frames split in half, thus even frames have
> * channels 0,1 and odd 2,3. */
> @@ -452,8 +467,10 @@ void ff_dv_offset_reset(DVDemuxContext *c, int64_t frame_offset)
> ************************************************************/
>
> typedef struct RawDVContext {
> + const AVClass *class;
> DVDemuxContext *dv_demux;
> uint8_t buf[DV_MAX_FRAME_SIZE];
> + int dvaudio_concealment;
> } RawDVContext;
>
> static int dv_read_timecode(AVFormatContext *s) {
> @@ -500,6 +517,7 @@ static int dv_read_header(AVFormatContext *s)
> c->dv_demux = avpriv_dv_init_demux(s);
> if (!c->dv_demux)
> return AVERROR(ENOMEM);
> + c->dv_demux->dvaudio_concealment = c->dvaudio_concealment;
>
> state = avio_rb32(s->pb);
> while ((state & 0xffffff7f) != 0x1f07003f) {
> @@ -639,6 +657,22 @@ static int dv_probe(const AVProbeData *p)
> return 0;
> }
>
> +#define OFFSET(x) offsetof(RawDVContext, x)
> +#define DEC AV_OPT_FLAG_DECODING_PARAM
> +static const AVOption dv_options[] = {
> + { "dvaudio_concealment", "", OFFSET(dvaudio_concealment), AV_OPT_TYPE_INT , {.i64 = AUDIO_CONCEAL_DROP}, 0, INT_MAX, DEC, "dvaudio_concealment"},
> + { "drop", "", 0 , AV_OPT_TYPE_CONST, {.i64 = AUDIO_CONCEAL_DROP}, 0, INT_MAX, DEC, "dvaudio_concealment"},
> + { "pass", "", 0 , AV_OPT_TYPE_CONST, {.i64 = AUDIO_CONCEAL_PASS}, 0, INT_MAX, DEC, "dvaudio_concealment"},
> + { NULL },
> +};
> +
> +static const AVClass dv_demuxer_class = {
> + .class_name = "DV demuxer",
> + .item_name = av_default_item_name,
> + .option = dv_options,
> + .version = LIBAVUTIL_VERSION_INT,
> +};
> +
> AVInputFormat ff_dv_demuxer = {
> .name = "dv",
> .long_name = NULL_IF_CONFIG_SMALL("DV (Digital Video)"),
> @@ -649,4 +683,5 @@ AVInputFormat ff_dv_demuxer = {
> .read_close = dv_read_close,
> .read_seek = dv_read_seek,
> .extensions = "dv,dif",
> + .priv_class = &dv_demuxer_class,
> };
> --
> 2.17.1
>
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