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MXF: improve ANC/VANC caption detection (fix #1647) #1831

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MXF: improve ANC/VANC caption detection (fix #1647) #1831

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62 changes: 47 additions & 15 deletions src/lib_ccx/ccx_demuxer_mxf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,8 @@ static int mxf_read_vanc_data(struct ccx_demuxer *demux, uint64_t size, struct d
unsigned char vanc_header[16];
uint8_t DID;
uint8_t SDID;
struct MXFContext *ctx = demux->private_data;

// uint8_t count; /* Currently unused */

if (size < 19)
Expand All @@ -378,14 +380,19 @@ static int mxf_read_vanc_data(struct ccx_demuxer *demux, uint64_t size, struct d
{
goto error;
}

SDID = buffered_get_byte(demux);
len++;
if (SDID == 0x01)
debug("Caption Type 708\n");
else if (SDID == 0x02)
debug("Caption Type 608\n");

SDID = buffered_get_byte(demux);
len++;
if (SDID == 0x01){
debug("Caption Type 708\n");
ctx->found_anc_captions = 1;
}
else if (SDID == 0x02){
debug("Caption Type 608\n");
ctx->found_anc_captions = 1;
}



cdp_size = buffered_get_byte(demux);
if (cdp_size + 19 > size)
{
Expand Down Expand Up @@ -555,6 +562,7 @@ int ccx_mxf_getmoredata(struct lib_ccx_ctx *ctx, struct demuxer_data **ppdata)
{
int ret = 0;
struct demuxer_data *data;
struct MXFContext *mxf;

if (!*ppdata)
{
Expand All @@ -575,7 +583,15 @@ int ccx_mxf_getmoredata(struct lib_ccx_ctx *ctx, struct demuxer_data **ppdata)
}

ret = read_packet(ctx->demux_ctx, data);

/* If MXF ANC captions were detected but no caption data was emitted yet,
avoid reporting a false "no captions found".
*/
mxf = ctx->demux_ctx->private_data;
if (ret <= 0 && mxf && mxf->found_anc_captions)
{
return 0;
}

return ret;
}

Expand All @@ -592,14 +608,30 @@ int ccx_probe_mxf(struct ccx_demuxer *ctx)
return CCX_FALSE;
}

// struct MXFContext *ccx_mxf_init(struct ccx_demuxer *demux)
// {
// struct MXFContext *ctx = NULL;

// ctx = malloc(sizeof(*ctx));
// if (!ctx)
// return NULL;

// memset(ctx, 0, sizeof(struct MXFContext));
// return ctx;
// }
struct MXFContext *ccx_mxf_init(struct ccx_demuxer *demux)
{
struct MXFContext *ctx = NULL;
struct MXFContext *ctx = NULL;

ctx = malloc(sizeof(*ctx));
if (!ctx)
return NULL;
ctx = malloc(sizeof(*ctx));
if (!ctx)
return NULL;

memset(ctx, 0, sizeof(struct MXFContext));
return ctx;
memset(ctx, 0, sizeof(struct MXFContext));

/* Track whether ANC caption packets are present */
ctx->found_anc_captions = 0;

return ctx;
}

1 change: 1 addition & 0 deletions src/lib_ccx/ccx_demuxer_mxf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ typedef struct MXFContext
MXFTrack tracks[32];
int nb_tracks;
int cap_count;
int found_anc_captions; // Flag to indicate if ANC captions have been found
struct ccx_rational edit_rate;
} MXFContext;

Expand Down