[FFmpeg-devel] [PATCH] avformat/dv: allow returning damaged audio
Marton Balint
cus at passwd.hu
Sat Oct 31 18:25:49 EET 2020
On Thu, 29 Oct 2020, Michael Niedermayer wrote:
> These potentially damaged packets are marked as corrupt.
> The packet length is predicted based on packet length history,
> allowing prediction of the common pattern used in NTSC.
>
> Fixes: Ticket8762
Sync loss is because of invalid timestamps, this is a possible workaround
for the ticket ignoring the core problem. I will post a patch to fix the
timestamps, it does not seem hard.
Regards,
Marton
> Tested-by: Dave Rice <dave at dericed.com>
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
> libavformat/dv.c | 60 ++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 53 insertions(+), 7 deletions(-)
>
> diff --git a/libavformat/dv.c b/libavformat/dv.c
> index 3e0d12c0e3..3499cba6f8 100644
> --- a/libavformat/dv.c
> +++ b/libavformat/dv.c
> @@ -34,12 +34,20 @@
> #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"
>
> +#define AS_HASH_SIZE 16
> +
> +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 +58,9 @@ struct DVDemuxContext {
> int ach;
> int frames;
> uint64_t abytes;
> + uint8_t as_pack[AS_HASH_SIZE][5];
> + uint8_t as_hash;
> + int dvaudio_concealment;
> };
>
> static inline uint16_t dv_audio_12to16(uint16_t sample)
> @@ -72,7 +83,7 @@ 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 +112,17 @@ 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) {
> + int index = (d->as_hash>>1) & (AS_HASH_SIZE-1);
> + if (frame[offs] == t) {
> + memcpy(d->as_pack[index], &frame[offs], sizeof(d->as_pack[index]));
> + } else if (d->as_pack[index][0] && d->dvaudio_concealment == AUDIO_CONCEAL_PASS) {
> + return d->as_pack[index];
> + } else if (d->as_pack[0][0] && d->dvaudio_concealment == AUDIO_CONCEAL_PASS) {
> + return d->as_pack[0];
> + }
> + }
> +
> return frame[offs] == t ? &frame[offs] : NULL;
> }
>
> @@ -116,7 +138,7 @@ 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 +146,7 @@ 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;
>
> @@ -137,6 +159,7 @@ static int dv_extract_audio(const uint8_t *frame, uint8_t **ppcm,
>
> if (freq >= FF_ARRAY_ELEMS(dv_audio_frequency))
> return AVERROR_INVALIDDATA;
> + c->as_hash = 2*c->as_hash + smpls;
>
> size = (sys->audio_min_samples[freq] + smpls) * 4; /* 2ch, 2bytes */
> half_ch = sys->difseg_size / 2;
> @@ -153,6 +176,9 @@ static int dv_extract_audio(const uint8_t *frame, uint8_t **ppcm,
> /* for each DIF channel */
> for (chan = 0; chan < sys->n_difchan; chan++) {
> av_assert0(ipcm<4);
> + c->audio_pkt[ipcm].flags &= ~AV_PKT_FLAG_CORRUPT;
> + if (as_pack >= c->as_pack[0] && as_pack < c->as_pack[AS_HASH_SIZE])
> + c->audio_pkt[ipcm].flags |= AV_PKT_FLAG_CORRUPT;
> pcm = ppcm[ipcm++];
> if (!pcm)
> break;
> @@ -224,7 +250,7 @@ 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 +318,7 @@ 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 +338,7 @@ 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_string2(tc, av_inv_q(c->sys->time_base), AV_RB32(tc_pack + 1), prevent_df, 1);
> @@ -392,7 +418,7 @@ 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. */
> @@ -460,8 +486,10 @@ 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) {
> @@ -502,6 +530,7 @@ static int dv_read_header(AVFormatContext *s)
>
> if ((ret = dv_init_demux(s, &c->dv_demux)) < 0)
> return ret;
> + c->dv_demux.dvaudio_concealment = c->dvaudio_concealment;
>
> state = avio_rb32(s->pb);
> while ((state & 0xffffff7f) != 0x1f07003f) {
> @@ -626,6 +655,22 @@ 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)"),
> @@ -635,4 +680,5 @@ AVInputFormat ff_dv_demuxer = {
> .read_packet = dv_read_packet,
> .read_seek = dv_read_seek,
> .extensions = "dv,dif",
> + .priv_class = &dv_demuxer_class,
> };
> --
> 2.17.1
>
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